GOETHE'S

THEORY OF COLOURS;

TRANSLATED FROM THE GERMAN:

WITH NOTES BY

CHARLES LOCK EASTLAKE, R.A., F.R.S.

"Cicero varietatem propriè in coloribus nasci, hinc in alienum migrare existimavit. Certè non alibi natura copiosius aut majore lasciviâ opes suas commendavit. Metalla, gemmas, marmora, flores, astra, omnia denique quæ progenuit suis etiam coloribus distinxit; ut venia debeatur si quis in tam numerosâ rerum sylvâ caligaverit."

CELIO CALCAGNINI.

LONDON:

JOHN MURRAY, ALBEMARLE STREET.

1840

[TO]

JEREMIAH HARMAN, Esq.

Dear Sir,

I dedicate to you the following translation as a testimony of my sincere gratitude and respect; in doing so, I but follow the example of Portius, an Italian writer, who inscribed his translation of Aristotle's Treatise on Colours to one of the Medici.

I have the honour to be,

Dear Sir,

Your most obliged and obedient Servant,

C. L. EASTLAKE.

[THE TRANSLATOR'S PREFACE.]

English writers who have spoken of Goethe's "Doctrine of Colours,"[1] have generally confined their remarks to those parts of the work in which he has undertaken to account for the colours of the prismatic spectrum, and of refraction altogether, on principles different from the received theory of Newton. The less questionable merits of the treatise consisting of a well-arranged mass of observations and experiments, many of which are important and interesting, have thus been in a great measure overlooked. The translator, aware of the opposition which the theoretical views alluded to have met with, intended at first to make a selection of such of the experiments as seem more directly applicable to the theory and practice of painting. Finding, however, that the alterations this would have involved would have been incompatible with a clear and connected view of the author's statements, he preferred giving the theory itself entire, reflecting, at the same time, that some scientific readers may be curious to hear the author speak for himself even on the points at issue.

In reviewing the history and progress of his opinions and researches, Goethe tells us that he first submitted his views to the public in two short essays entitled "Contributions to Optics." Among the circumstances which he supposes were unfavourable to him on that occasion, he mentions the choice of his title, observing that by a reference to optics he must have appeared to make pretensions to a knowledge of mathematics, a science with which he admits he was very imperfectly acquainted. Another cause to which he attributes the severe treatment he experienced, was his having ventured so openly to question the truth of the established theory: but this last provocation could not be owing to mere inadvertence on his part; indeed the larger work, in which he alludes to these circumstances, is still more remarkable for the violence of his objections to the Newtonian doctrine.

There can be no doubt, however, that much of the opposition Goethe met with was to be attributed to the manner as well as to the substance of his statements. Had he contented himself with merely detailing his experiments and showing their application to the laws of chromatic harmony, leaving it to others to reconcile them as they could with the pre-established system, or even to doubt in consequence, the truth of some of the Newtonian conclusions, he would have enjoyed the credit he deserved for the accuracy and the utility of his investigations. As it was, the uncompromising expression of his convictions only exposed him to the resentment or silent neglect of a great portion of the scientific world, so that for a time he could not even obtain a fair hearing for the less objectionable or rather highly valuable communications contained in his book. A specimen of his manner of alluding to the Newtonian theory will be seen in the preface.

It was quite natural that this spirit should call forth a somewhat vindictive feeling, and with it not a little uncandid as well as unsparing criticism. "The Doctrine of Colours" met with this reception in Germany long before it was noticed in England, where a milder and fairer treatment could hardly be expected, especially at a time when, owing perhaps to the limited intercourse with the continent, German literature was far less popular than it is at present. This last fact, it is true, can be of little importance in the present instance, for although the change of opinion with regard to the genius of an enlightened nation must be acknowledged to be beneficial, it is to be hoped there is no fashion in science, and the translator begs to state once for all, that in advocating the neglected merits of the "Doctrine of Colours," he is far from undertaking to defend its imputed errors. Sufficient time has, however, now elapsed since the publication of this work (in 1810) to allow a calmer and more candid examination of its claims. In this more pleasing task Germany has again for some time led the way, and many scientific investigators have followed up the hints and observations of Goethe with a due acknowledgment of the acuteness of his views.[2]

It may require more magnanimity in English scientific readers to do justice to the merits of one who was so open and, in many respects, it is believed, so mistaken an opponent of Newton; but it must be admitted that the statements of Goethe contain more useful principles in all that relates to harmony of colour than any that have been derived from the established doctrine. It is no derogation of the more important truths of the Newtonian theory to say, that the views it contains seldom appear in a form calculated for direct application to the arts. The principle of contrast, so universally exhibited in nature, so apparent in the action and re-action of the eye itself, is scarcely hinted at. The equal pretensions of seven colours, as such, and the fanciful analogies which their assumed proportions could suggest, have rarely found favour with the votaries of taste,—indeed they have long been abandoned even by scientific authorities.[3] And here the translator stops: he is quite aware that the defects which make the Newtonian theory so little available for æsthetic application, are far from invalidating its more important conclusions in the opinion of most scientific men. In carefully abstaining therefore from any comparison between the two theories in these latter respects, he may still be permitted to advocate the clearness and fulness of Goethe's experiments. The German philosopher reduces the colours to their origin and simplest elements; he sees and constantly bears in mind, and sometimes ably elucidates, the phenomena of contrast and gradation, two principles which may be said to make up the artist's world, and to constitute the chief elements of beauty. These hints occur mostly in what may be called the scientific part of the work. On the other hand, in the portion expressly devoted to the æsthetic application of the doctrine, the author seems to have made but an inadequate use of his own principles.

In that part of the chapter on chemical colours which relates to the colours of plants and animals, the same genius and originality which are displayed in the Essays on Morphology, and which have secured to Goethe undisputed rank among the investigators of nature, are frequently apparent.

But one of the most interesting features of Goethe's theory, although it cannot be a recommendation in a scientific point of view, is, that it contains, undoubtedly with very great improvements, the general doctrine of the ancients and of the Italians at the revival of letters. The translator has endeavoured, in some notes, to point out the connexion between this theory and the practice of the Italian painters.

The "Doctrine of Colours," as first published in 1810, consists of two volumes in 8vo., and sixteen plates, with descriptions, in 4to. It is divided into three parts, a didactic, a controversial, and an historical part; the present translation is confined to the first of these, with such extracts from the other two as seemed necessary, in fairness to the author, to explain some of his statements. The polemical and historical parts are frequently alluded to in the preface and elsewhere in the present work, but it has not been thought advisable to omit these allusions. No alterations whatever seem to have been made by Goethe in the didactic portion in later editions, but he subsequently wrote an additional chapter on entoptic colours, expressing his wish that it might be inserted in the theory itself at a particular place which he points out. The form of this additional essay is, however, very different from that of the rest of the work, and the translator has therefore merely given some extracts from it in the appendix. The polemical portion has been more than once omitted in later editions.

In the two first parts the author's statements are arranged numerically, in the style of Bacon's Natural History. This, we are told, was for the convenience of reference; but many passages are thus separately numbered which hardly seem to have required it. The same arrangement is, however, strictly followed in the translation to facilitate a comparison with the original where it may be desired; and here the translator observes, that although he has sometimes permitted himself to make slight alterations, in order to avoid unnecessary repetition, or to make the author's meaning clearer, he feels that an apology may rather be expected from him for having omitted so little. He was scrupulous on this point, having once determined to translate the whole treatise, partly, as before stated, from a wish to deal fairly with a controversial writer, and partly because many passages, not directly bearing on the scientific views, are still characteristic of Goethe. The observations which the translator has ventured to add are inserted in the appendix: these observations are chiefly confined to such of the author's opinions and conclusions as have direct reference to the arts; they seldom interfere with the scientific propositions, even where these have been considered most vulnerable.

[1] "Farbenlehre"—in the present translation generally rendered "Theory of Colours."

[2] Sixteen years after the appearance of the Farbenlehre, Dr. Johannes Müller devoted a portion of his work, "Zur vergleichenden Physiologie des Gesichtssinnes des Menschen und der Thiere," to the critical examination of Goethe's theory. In his introductory remarks he expresses himself as follows—"For my own part I readily acknowledge that I have been greatly indebted to Goethe's treatise, and can truly say that without having studied it for some years in connexion with the actual phenomena, the present work would hardly have been undertaken. I have no hesitation in confessing more particularly that I have full faith in Goethe's statements, where they are merely descriptive of the phenomena, and where the author does not enter into explanations involving a decision on the great points of controversy." The names of Hegel, Schelling, Seebeck, Steffens, may also be mentioned, and many others might be added, as authorities more or less favourable to the Farbenlehre.

[3] "When Newton attempted to reckon up the rays of light decomposed by the prism," says Sir John Leslie, "and ventured to assign the famous number seven, he was apparently influenced by some lurking disposition towards mysticism. If any unprejudiced person will fairly repeat the experiment, he must soon be convinced that the various coloured spaces which paint the spectrum slide into each other by indefinite shadings: he may name four or five principal colours, but the subordinate spaces are evidently so multiplied as to be incapable of enumeration. The same illustrious mathematician, we can hardly doubt, was betrayed by a passion for analogy, when he imagined that the primary colours are distributed over the spectrum after the proportions of the diatonic scale of music, since those intermediate spaces have really no precise and defined limits."—Treatises on Various Subjects of Natural and Chemical Philosophy, p. 59.

[PREFACE TO THE FIRST EDITION OF 1810.]

It may naturally be asked whether, in proposing to treat of colours, light itself should not first engage our attention: to this we briefly and frankly answer that since so much has already been said on the subject of light, it can hardly be desirable to multiply repetitions by again going over the same ground.

Indeed, strictly speaking, it is useless to attempt to express the nature of a thing abstractedly. Effects we can perceive, and a complete history of those effects would, in fact, sufficiently define the nature of the thing itself. We should try in vain to describe a man's character, but let his acts be collected and an idea of the character will be presented to us.

The colours are acts of light; its active and passive modifications: thus considered we may expect from them some explanation respecting light itself. Colours and light, it is true, stand in the most intimate relation to each other, but we should think of both as belonging to nature as a whole, for it is nature as a whole which manifests itself by their means in an especial manner to the sense of sight.

The completeness of nature displays itself to another sense in a similar way. Let the eye be closed, let the sense of hearing be excited, and from the lightest breath to the wildest din, from the simplest sound to the highest harmony, from the most vehement and impassioned cry to the gentlest word of reason, still it is Nature that speaks and manifests her presence, her power, her pervading life and the vastness of her relations; so that a blind man to whom the infinite visible is denied, can still comprehend an infinite vitality by means of another organ.

And thus as we descend the scale of being, Nature speaks to other senses—to known, misunderstood, and unknown senses: so speaks she with herself and to us in a thousand modes. To the attentive observer she is nowhere dead nor silent; she has even a secret agent in inflexible matter, in a metal, the smallest portions of which tell us what is passing in the entire mass. However manifold, complicated, and unintelligible this language may often seem to us, yet its elements remain ever the same. With light poise and counterpoise, Nature oscillates within her prescribed limits, yet thus arise all the varieties and conditions of the phenomena which are presented to us in space and time.

Infinitely various are the means by which we become acquainted with these general movements and tendencies: now as a simple repulsion and attraction, now as an upsparkling and vanishing light, as undulation in the air, as commotion in matter, as oxydation and de-oxydation; but always, uniting or separating, the great purpose is found to be to excite and promote existence in some form or other.

The observers of nature finding, however, that this poise and counterpoise are respectively unequal in effect, have endeavoured to represent such a relation in terms. They have everywhere remarked and spoken of a greater and lesser principle, an action and resistance, a doing and suffering, an advancing and retiring, a violent and moderating power; and thus a symbolical language has arisen, which, from its close analogy, may be employed as equivalent to a direct and appropriate terminology.

To apply these designations, this language of Nature to the subject we have undertaken: to enrich and amplify this language by means of the theory of colours and the variety of their phenomena, and thus facilitate the communication of higher theoretical views, was the principal aim of the present treatise.

The work itself is divided into three parts. The first contains the outline of a theory of colours. In this, the innumerable cases which present themselves to the observer are collected under certain leading phenomena, according to an arrangement which will be explained in the Introduction; and here it may be remarked, that although we have adhered throughout to experiment, and throughout considered it as our basis, yet the theoretical views which led to the arrangement alluded to, could not but be stated. It is sometimes unreasonably required by persons who do not even themselves attend to such a condition, that experimental information should be submitted without any connecting theory to the reader or scholar, who is himself to form his conclusions as he may list. Surely the mere inspection of a subject can profit us but little. Every act of seeing leads to consideration, consideration to reflection, reflection to combination, and thus it may be said that in every attentive look on nature we already theorise. But in order to guard against the possible abuse of this abstract view, in order that the practical deductions we look to should be really useful, we should theorise without forgetting that we are so doing, we should theorise with mental self-possession, and, to use a bold word, with irony.

In the second part[1] we examine the Newtonian theory; a theory which by its ascendancy and consideration has hitherto impeded a free inquiry into the phenomena of colours. We combat that hypothesis, for although it is no longer found available, it still retains a traditional authority in the world. Its real relations to its subject will require to be plainly pointed out; the old errors must be cleared away, if the theory of colours is not still to remain in the rear of so many other better investigated departments of natural science. Since, however, this second part of our work may appear somewhat dry as regards its matter, and perhaps too vehement and excited in its manner, we may here be permitted to introduce a sort of allegory in a lighter style, as a prelude to that graver portion, and as some excuse for the earnestness alluded to.

We compare the Newtonian theory of colours to an old castle, which was at first constructed by its architect with youthful precipitation; it was, however, gradually enlarged and equipped by him according to the exigencies of time and circumstances, and moreover was still further fortified and secured in consequence of feuds and hostile demonstrations.

The same system was pursued by his successors and heirs: their increased wants within, the harassing vigilance of their opponents without, and various accidents compelled them in some places to build near, in others in connexion with the fabric, and thus to extend the original plan.

It became necessary to connect all these incongruous parts and additions by the strangest galleries, halls and passages. All damages, whether inflicted by the hand of the enemy or the power of time, were quickly made good. As occasion required, they deepened the moats, raised the walls, and took care there should be no lack of towers, battlements, and embrasures. This care and these exertions gave rise to a prejudice in favour of the great importance of the fortress, and still upheld that prejudice, although the arts of building and fortification were by this time very much advanced, and people had learnt to construct much better dwellings and defences in other cases. But the old castle was chiefly held in honour because it had never been taken, because it had repulsed so many assaults, had baffled so many hostile operations, and had always preserved its virgin renown. This renown, this influence lasts even now: it occurs to no one that the old castle is become uninhabitable. Its great duration, its costly construction, are still constantly spoken of. Pilgrims wend their way to it; hasty sketches of it are shown in all schools, and it is thus recommended to the reverence of susceptible youth. Meanwhile, the building itself is already abandoned; its only inmates are a few invalids, who in simple seriousness imagine that they are prepared for war.

Thus there is no question here respecting a tedious siege or a doubtful war; so far from it we find this eighth wonder of the world already nodding to its fall as a deserted piece of antiquity, and begin at once, without further ceremony, to dismantle it from gable and roof downwards; that the sun may at last shine into the old nest of rats and owls, and exhibit to the eye of the wondering traveller that labyrinthine, incongruous style of building, with its scanty, make-shift contrivances, the result of accident and emergency, its intentional artifice and clumsy repairs. Such an inspection will, however, only be possible when wall after wall, arch after arch, is demolished, the rubbish being at once cleared away as well as it can be.

To effect this, and to level the site where it is possible to do so, to arrange the materials thus acquired, so that they can be hereafter again employed for a new building, is the arduous duty we have undertaken in this Second Part. Should we succeed, by a cheerful application of all possible ability and dexterity, in razing this Bastille, and in gaining a free space, it is thus by no means intended at once to cover the site again and to encumber it with a new structure; we propose rather to make use of this area for the purpose of passing in review a pleasing and varied series of illustrative figures.

The third part is thus devoted to the historical account of early inquirers and investigators. As we before expressed the opinion that the history of an individual displays his character, so it may here be well affirmed that the history of science is science itself. We cannot clearly be aware of what we possess till we have the means of knowing what others possessed before us. We cannot really and honestly rejoice in the advantages of our own time if we know not how to appreciate the advantages of former periods. But it was impossible to write, or even to prepare the way for a history of the theory of colours while the Newtonian theory existed; for no aristocratic presumption has ever looked down on those who were not of its order, with such intolerable arrogance as that betrayed by the Newtonian school in deciding on all that had been done in earlier times and all that was done around it. With disgust and indignation we find Priestley, in his History of Optics, like many before and after him, dating the success of all researches into the world of colours from the epoch of a decomposed ray of light, or what pretended to be so; looking down with a supercilious air on the ancient and less modern inquirers, who, after all, had proceeded quietly in the right road, and who have transmitted to us observations and thoughts in detail which we can neither arrange better nor conceive more justly.

We have a right to expect from one who proposes to give the history of any science, that he inform us how the phenomena of which it treats were gradually known, and what was imagined, conjectured, assumed, or thought respecting them. To state all this in due connexion is by no means an easy task; need we say that to write a history at all is always a hazardous affair; with the most honest intention there is always a danger of being dishonest; for in such an undertaking, a writer tacitly announces at the outset that he means to place some things in light, others in shade. The author has, nevertheless, long derived pleasure from the prosecution of his task: but as it is the intention only that presents itself to the mind as a whole, while the execution is generally accomplished portion by portion, he is compelled to admit that instead of a history he furnishes only materials for one. These materials consist in translations, extracts, original and borrowed comments, hints, and notes; a collection, in short, which, if not answering all that is required, has at least the merit of having been made with earnestness and interest. Lastly, such materials,—not altogether untouched it is true, but still not exhausted,—may be more satisfactory to the reflecting reader in the state in which they are, as he can easily combine them according to his own judgment.

This third part, containing the history of the science, does not, however, thus conclude the subject: a fourth supplementary portion[2] is added. This contains a recapitulation or revision; with a view to which, chiefly, the paragraphs are headed numerically. In the execution of a work of this kind some things may be forgotten, some are of necessity omitted, so as not to distract the attention, some can only be arrived at as corollaries, and others may require to be exemplified and verified: on all these accounts, postscripts, additions and corrections are indispensable. This part contains, besides, some detached essays; for example, that on the atmospheric colours; for as these are introduced in the theory itself without any classification, they are here presented to the mind's eye at one view. Again, if this essay invites the reader to consult Nature herself, another is intended to recommend the artificial aids of science by circumstantially describing the apparatus which will in future be necessary to assist researches into the theory of colours.

In conclusion, it only remains to speak of the plates which are added at the end of the work;[3] and here we confess we are reminded of that incompleteness and imperfection which the present undertaking has, in common with all others of its class; for as a good play can be in fact only half transmitted to writing, a great part of its effect depending on the scene, the personal qualities of the actor, the powers of his voice, the peculiarities of his gestures, and even the spirit and favourable humour of the spectators; so it is, in a still greater degree, with a book which treats of the appearances of nature. To be enjoyed, to be turned to account, Nature herself must be present to the reader, either really, or by the help of a lively imagination. Indeed, the author should in such cases communicate his observations orally, exhibiting the phenomena he describes—as a text, in the first instance,—partly as they appear to us unsought, partly as they may be presented by contrivance to serve in particular illustration. Explanation and description could not then fail to produce a lively impression.

The plates which generally accompany works like the present are thus a most inadequate substitute for all this; a physical phenomenon exhibiting its effects on all sides is not to be arrested in lines nor denoted by a section. No one ever dreams of explaining chemical experiments with figures; yet it is customary in physical researches nearly allied to these, because the object is thus found to be in some degree answered. In many cases, however, such diagrams represent mere notions; they are symbolical resources, hieroglyphic modes of communication, which by degrees assume the place of the phenomena and of Nature herself, and thus rather hinder than promote true knowledge. In the present instance we could not dispense with plates, but we have endeavoured so to construct them that they may be confidently referred to for the explanation of the didactic and polemical portions. Some of these may even be considered as forming part of the apparatus before mentioned.

We now therefore refer the reader to the work itself; first, only repeating a request which many an author has already made in vain, and which the modern German reader, especially, so seldom grants:—

Si quid novisti rectius istis
Candidus imperti; si non, his utere mecum.

[1] The Polemical part.

[2] This preface must have been written before the work was finished, for at the conclusion of the historical part there is only an apology for the non-appearance of the supplement here alluded to.

[3] In the present translation the necessary plates accompany the text.

[CONTENTS]

PART IV.
GENERAL CHARACTERISTICS.

The Facility with which Colour appears [274]
The Definite Nature of Colour [276]
Combination of the Two Principles [277]
Augmentation to Red [277]
Junction of the Two Augmented Extremes [278]
Completeness the Result of Variety in Colour [279]
Harmony of the Complete State [280]
Facility with which Colour may be made to tend either to
the Plus or Minus side [281]
Evanescence of Colour [281]
Permanence of Colour [282]

PART V.
RELATION TO OTHER PURSUITS.

Relation to Philosophy [283]
Relation to Mathematics [286]
Relation to the Technical Operations of the Dyer [289]
Relation to Physiology and Pathology [291]
Relation to Natural History [292]
Relation to General Physics [293]
Relation to the Theory of Music [298]
Concluding Observations on Terminology [300]

PART VI.
EFFECT OF COLOUR WITH REFERENCE
TO MORAL ASSOCIATIONS.

Yellow [306]
Red-Yellow [308]
Yellow-Red [309]
Blue [310]
Red-Blue [312]
Blue-Red [313]
Red [313]
Green [316]
Completeness and Harmony [316]
Characteristic Combinations [321]
Yellow and Blue [322]
Yellow and Red [322]
Blue and Red [322]
Yellow-Red and Blue-Red [323]
Combinations Non-Characteristic [324]
Relation of the Combinations to Light and Dark [325]
Considerations derived from the Evidence of Experience
and History [326]
Æsthetic Influence [330]
Chiaro-Scuro [331]
Tendency to Colour [334]
Keeping [335]
Colouring [337]
Colour in General Nature [337]
Colour of Particular Objects [338]
Characteristic Colouring [339]
Harmonious Colouring [341]
Genuine Tone [342]
False Tone [342]
Weak Colouring [343]
The Motley [344]
Dread of Theory [344]
Ultimate Aim [345]
Grounds [345]
Pigments [348]
Allegorical, Symbolical, Mystical Application of Colour [350]
Concluding Observations [352]

[OUTLINE OF A THEORY OF COLOURS.]

"Si vera nostra sunt aut falsa, erunt talia, licet nostra per vitam defendimus. Post fata nostra pueri qui nunc ludunt nostri judices erunt."

[INTRODUCTION.]

The desire of knowledge is first stimulated in us when remarkable phenomena attract our attention. In order that this attention be continued, it is necessary that we should feel some interest in exercising it, and thus by degrees we become better acquainted with the object of our curiosity. During this process of observation we remark at first only a vast variety which presses indiscriminately on our view; we are forced to separate, to distinguish, and again to combine; by which means at last a certain order arises which admits of being surveyed with more or less satisfaction.

To accomplish this, only in a certain degree, in any department, requires an unremitting and close application; and we find, for this reason, that men prefer substituting a general theoretical view, or some system of explanation, for the facts themselves, instead of taking the trouble to make themselves first acquainted with cases in detail and then constructing a whole.

The attempt to describe and class the phenomena of colours has been only twice made: first by Theophrastus,[1] and in modern times by Boyle. The pretensions of the present essay to the third place will hardly be disputed.

Our historical survey enters into further details. Here we merely observe that in the last century such a classification was not to be thought of, because Newton had based his hypothesis on a phenomenon exhibited in a complicated and secondary state; and to this the other cases that forced themselves on the attention were contrived to be referred, when they could not be passed over in silence; just as an astronomer would do, if from whim he were to place the moon in the centre of our system; he would be compelled to make the earth, sun, and planets revolve round the lesser body, and be forced to disguise and gloss over the error of his first assumption by ingenious calculations and plausible statements.

In our prefatory observations we assumed the reader to be acquainted with what was known respecting light; here we assume the same with regard to the eye. We observed that all nature manifests itself by means of colours to the sense of sight. We now assert, extraordinary as it may in some degree appear, that the eye sees no form, inasmuch as light, shade, and colour together constitute that which to our vision distinguishes object from object, and the parts of an object from each other. From these three, light, shade, and colour, we construct the visible world, and thus, at the same time, make painting possible, an art which has the power of producing on a flat surface a much more perfect visible world than the actual one can be.

The eye may be said to owe its existence to light, which calls forth, as it were, a sense that is akin to itself; the eye, in short, is formed with reference to light, to be fit for the action of light; the light it contains corresponding with the light without.

We are here reminded of a significant adage in constant use with the ancient Ionian school—"Like is only known by Like;" and again, of the words of an old mystic writer, which may be thus rendered, "If the eye were not sunny, how could we perceive light? If God's own strength lived not in us, how could we delight in Divine things?" This immediate affinity between light and the eye will be denied by none; to consider them as identical in substance is less easy to comprehend. It will be more intelligible to assert that a dormant light resides in the eye, and that it may be excited by the slightest cause from within or from without. In darkness we can, by an effort of imagination, call up the brightest images; in dreams objects appear to us as in broad daylight; awake, the slightest external action of light is perceptible, and if the organ suffers an actual shock, light and colours spring forth. Here, however, those who are wont to proceed according to a certain method, may perhaps observe that as yet we have not decidedly explained what colour is. This question, like the definition of light and the eye, we would for the present evade, and would appeal to our inquiry itself, where we have circumstantially shown how colour is produced. We have only therefore to repeat that colour is a law of nature in relation with the sense of sight. We must assume, too, that every one has this sense, that every one knows the operation of nature on it, for to a blind man it would be impossible to speak of colours.

That we may not, however, appear too anxious to shun such an explanation, we would restate what has been said as follows: colour is an elementary phenomenon in nature adapted to the sense of vision; a phenomenon which, like all others, exhibits itself by separation and contrast, by commixture and union, by augmentation and neutralization, by communication and dissolution: under these general terms its nature may be best comprehended.

We do not press this mode of stating the subject on any one. Those who, like ourselves, find it convenient, will readily adopt it; but we have no desire to enter the lists hereafter in its defence. From time immemorial it has been dangerous to treat of colour; so much so, that one of our predecessors ventured on a certain occasion to say, "The ox becomes furious if a red cloth is shown to him; but the philosopher, who speaks of colour only in a general way, begins to rave."

Nevertheless, if we are to proceed to give some account of our work, to which we have appealed, we must begin by explaining how we have classed the different conditions under which colour is produced. We found three modes in which it appears; three classes of colours, or rather three exhibitions of them all. The distinctions of these classes are easily expressed.

Thus, in the first instance, we considered colours, as far as they may be said to belong to the eye itself, and to depend on an action and re-action of the organ; next, they attracted our attention as perceived in, or by means of, colourless mediums; and lastly, where we could consider them as belonging to particular substances. We have denominated the first, physiological, the second, physical, the third, chemical colours. The first are fleeting and not to be arrested; the next are passing, but still for a while enduring; the last may be made permanent for any length of time.

Having separated these classes and kept them as distinct as possible, with a view to a clear, didactic exposition, we have been enabled at the same time to exhibit them in an unbroken series, to connect the fleeting with the somewhat more enduring, and these again with the permanent hues; and thus, after having carefully attended to a distinct classification in the first instance, to do away with it again when a larger view was desirable.

In a fourth division of our work we have therefore treated generally what was previously detailed under various particular conditions, and have thus, in fact, given a sketch for a future theory of colours. We will here only anticipate our statements so far as to observe, that light and darkness, brightness and obscurity, or if a more general expression is preferred, light and its absence, are necessary to the production of colour. Next to the light, a colour appears which we call yellow; another appears next to the darkness, which we name blue. When these, in their purest state, are so mixed that they are exactly equal, they produce a third colour called green. Each of the two first-named colours can however of itself produce a new tint by being condensed or darkened. They thus acquire a reddish appearance which can be increased to so great a degree that the original blue or yellow is hardly to be recognised in it: but the intensest and purest red, especially in physical cases, is produced when the two extremes of the yellow-red and blue-red are united. This is the actual state of the appearance and generation of colours. But we can also assume an existing red in addition to the definite existing blue and yellow, and we can produce contrariwise, by mixing, what we directly produced by augmentation or deepening. With these three or six colours, which may be conveniently included in a circle, the elementary doctrine of colours is alone concerned. All other modifications, which may be extended to infinity, have reference more to the application,—have reference to the technical operations of the painter and dyer, and the various purposes of artificial life. To point out another general quality, we may observe that colours throughout are to be considered as half-lights, as half-shadows, on which account if they are so mixed as reciprocally to destroy their specific hues, a shadowy tint, a grey, is produced.

In the fifth division of our inquiry we had proposed to point out the relations in which we should wish our doctrine of colours to stand to other pursuits. Important as this part of our work is, it is perhaps on this very account not so successful as we could wish. Yet when we reflect that strictly speaking these relations cannot be described before they exist, we may console ourselves if we have in some degree failed in endeavouring for the first time to define them. For undoubtedly we should first wait to see how those whom we have endeavoured to serve, to whom we have intended to make an agreeable and useful offering, how such persons, we say, will accept the result of our utmost exertion: whether they will adopt it, whether they will make use of it and follow it up, or whether they will repel, reject, and suffer it to remain unassisted and neglected.

Meanwhile, we venture to express what we believe and hope. From the philosopher we believe we merit thanks for having traced the phenomena of colours to their first sources, to the circumstances under which they simply appear and are, and beyond which no further explanation respecting them is possible. It will, besides, be gratifying to him that we have arranged the appearances described in a form that admits of being easily surveyed, even should he not altogether approve of the arrangement itself.

The medical practitioner, especially him whose study it is to watch over the organ of sight, to preserve it, to assist its defects and to cure its disorders, we reckon to make especially our friend. In the chapter on the physiological colours, in the Appendix relating to those that are more strictly pathological, he will find himself quite in his own province. We are not without hopes of seeing the physiological phenomena,—a hitherto neglected, and, we may add, most important branch of the theory of colours,—completely investigated through the exertions of those individuals who in our own times are treating this department with success.

The investigator of nature should receive us cordially, since we enable him to exhibit the doctrine of colours in the series of other elementary phenomena, and at the same time enable him to make use of a corresponding nomenclature, nay, almost the same words and designations as under the other rubrics. It is true we give him rather more trouble as a teacher, for the chapter of colours is not now to be dismissed as heretofore with a few paragraphs and experiments; nor will the scholar submit to be so scantily entertained as he has hitherto been, without murmuring. On the other hand, an advantage will afterwards arise out of this: for if the Newtonian doctrine was easily learnt, insurmountable difficulties presented themselves in its application. Our theory is perhaps more difficult to comprehend, but once known, all is accomplished, for it carries its application along with it.

The chemist who looks upon colours as indications by which he may detect the more secret properties of material things, has hitherto found much inconvenience in the denomination and description of colours; nay, some have been induced after closer and nicer examination to look upon colour as an uncertain and fallacious criterion in chemical operations. Yet we hope by means of our arrangement and the nomenclature before alluded to, to bring colour again into credit, and to awaken the conviction that a progressive, augmenting, mutable quality, a quality which admits of alteration even to inversion, is not fallacious, but rather calculated to bring to light the most delicate operations of nature.

In looking a little further round us, we are not without fears that we may fail to satisfy another class of scientific men. By an extraordinary combination of circumstances the theory of colours has been drawn into the province and before the tribunal of the mathematician, a tribunal to which it cannot be said to be amenable. This was owing to its affinity with the other laws of vision which the mathematician was legitimately called upon to treat. It was owing, again, to another circumstance: a great mathematician had investigated the theory of colours, and having been mistaken in his observations as an experimentalist, he employed the whole force of his talent to give consistency to this mistake. Were both these circumstances considered, all misunderstanding would presently be removed, and the mathematician would willingly co-operate with us, especially in the physical department of the theory.

To the practical man, to the dyer, on the other hand, our labour must be altogether acceptable; for it was precisely those who reflected on the facts resulting from the operations of dyeing who were the least satisfied with the old theory: they were the first who perceived the insufficiency of the Newtonian doctrine. The conclusions of men are very different according to the mode in which they approach a science or branch of knowledge; from which side, through which door they enter. The literally practical man, the manufacturer, whose attention is constantly and forcibly called to the facts which occur under his eye, who experiences benefit or detriment from the application of his convictions, to whom loss of time and money is not indifferent, who is desirous of advancing, who aims at equalling or surpassing what others have accomplished,—such a person feels the unsoundness and erroneousness of a theory much sooner than the man of letters, in whose eyes words consecrated by authority are at last equivalent to solid coin; than the mathematician, whose formula always remains infallible, even although the foundation on which it is constructed may not square with it. Again, to carry on the figure before employed, in entering this theory from the side of painting, from the side of æsthetic[2] colouring generally, we shall be found to have accomplished a most thank-worthy office for the artist. In the sixth part we have endeavoured to define the effects of colour as addressed at once to the eye and mind, with a view to making them more available for the purposes of art. Although much in this portion, and indeed throughout, has been suffered to remain as a sketch, it should be remembered that all theory can in strictness only point out leading principles, under the guidance of which, practice may proceed with vigour and be enabled to attain legitimate results.

[1] The treatise to which the author alludes in more generally ascribed to Aristotle.—T.

[2] Æsthetic—belonging to taste as mere internal sense, from αἰσθάνομαι, to feel; the word was first used by Wolf.—T.

[PART I.]

PHYSIOLOGICAL COLOURS.

1.

We naturally place these colours first, because they belong altogether, or in a great degree, to the subject[1]—to the eye itself. They are the foundation of the whole doctrine, and open to our view the chromatic harmony on which so much difference of opinion has existed. They have been hitherto looked upon as extrinsic and casual, as illusion and infirmity: their appearances have been known from ancient date; but, as they were too evanescent to be arrested, they were banished into the region of phantoms, and under this idea have been very variously described.

[2.]

Thus they are called colores adventicii by Boyle; imaginarii and phantastici by Rizetti; by Buffon, couleurs accidentelles; by Scherfer, scheinfarben (apparent colours); ocular illusions and deceptions of sight by many; by Hamberger, vitia fugitiva; by Darwin, ocular spectra.

[3.]

We have called them physiological because they belong to the eye in a healthy state; because we consider them as the necessary conditions of vision; the lively alternating action of which, with reference to external objects and a principle within it, is thus plainly indicated.

[4.]

To these we subjoin the pathological colours, which, like all deviations from a constant law, afford a more complete insight into the nature of the physiological colours.

I

EFFECTS OF LIGHT AND DARKNESS ON THE EYE.

[5.]

The retina, after being acted upon by light or darkness, is found to be in two different states, which are entirely opposed to each other.

[6.]

If we keep the eyes open in a totally dark place, a certain sense of privation is experienced. The organ is abandoned to itself; it retires into itself. That stimulating and grateful contact is wanting by means of which it is connected with the external world, and becomes part of a whole.

[7.]

If we look on a white, strongly illumined surface, the eye is dazzled, and for a time is incapable of distinguishing objects moderately lighted.

[8.]

The whole of the retina is acted on in each of these extreme states, and thus we can only experience one of these effects at a time. In the one case (6) we found the organ in the utmost relaxation and susceptibility; in the other (7) in an overstrained state, and scarcely susceptible at all.

[9.]

If we pass suddenly from the one state to the other, even without supposing these to be the extremes, but only, perhaps, a change from bright to dusky, the difference is remarkable, and we find that the effects last for some time.

[10.]

In passing from bright daylight to a dusky place we distinguish nothing at first: by degrees the eye recovers its susceptibility; strong eyes sooner than weak ones; the former in a minute, while the latter may require seven or eight minutes.

[11.]

The fact that the eye is not susceptible to faint impressions of light, if we pass from light to comparative darkness, has led to curious mistakes in scientific observations. Thus an observer, whose eyes required some time to recover their tone, was long under the impression that rotten wood did not emit light at noon-day, even in a dark room. The fact was, he did not see the faint light, because he was in the habit of passing from bright sunshine to the dark room, and only subsequently remained so long there that the eye had time to recover itself.

The same may have happened to Doctor Wall, who, in the daytime, even in a dark room, could hardly perceive the electric light of amber.

Our not seeing the stars by day, as well as the improved appearance of pictures seen through a double tube, is also to be attributed to the same cause.

[12.]

If we pass from a totally dark place to one illumined by the sun, we are dazzled. In coming from a lesser degree of darkness to light that is not dazzling, we perceive all objects clearer and better: hence eyes that have been in a state of repose are in all cases better able to perceive moderately distinct appearances.

Prisoners who have been long confined in darkness acquire so great a susceptibility of the retina, that even in the dark (probably a darkness very slightly illumined) they can still distinguish objects.

[13.]

In the act which we call seeing, the retina is at one and the same time in different and even opposite states. The greatest brightness, short of dazzling, acts near the greatest darkness. In this state we at once perceive all the intermediate gradations of chiaro-scuro, and all the varieties of hues.

[14.]

We will proceed in due order to consider and examine these elements of the visible world, as well as the relation in which the organ itself stands to them, and for this purpose we take the simplest objects.

[1] The German distinction between subject and object is so generally understood and adopted, that it is hardly necessary to explain that the subject is the individual, in this case the beholder; the object, all that is without him.—T.

[II.]

EFFECTS OF BLACK AND WHITE OBJECTS ON THE EYE.

[15.]

In the same manner as the retina generally is affected by brightness and darkness, so it is affected by single bright or dark objects. If light and dark produce different results on the whole retina, so black and white objects seen at the same time produce the same states together which light and dark occasioned in succession.

[16.]

A dark object appears smaller than a bright one of the same size. Let a white disk be placed on a black ground, and a black disk on a white ground, both being exactly similar in size; let them be seen together at some distance, and we shall pronounce the last to be about a fifth part smaller than the other. If the black circle be made larger by so much, they will appear equal.[1]

[17.]

Thus Tycho de Brahe remarked that the moon in conjunction (the darker state) appears about a fifth part smaller than when in opposition (the bright full state). The first crescent appears to belong to a larger disk than the remaining dark portion, which can sometimes be distinguished at the period of the new moon. Black dresses make people appear smaller than light ones. Lights seen behind an edge make an apparent notch in it. A ruler, behind which the flame of a light just appears, seems to us indented. The rising or setting sun appears to make a notch in the horizon.

Plate 1.

[18.]

Black, as the equivalent of darkness, leaves the organ in a state of repose; white, as the representative of light, excites it. We may, perhaps, conclude from the above experiment (16) that the unexcited retina, if left to itself, is drawn together, and occupies a less space than in its active state, produced by the excitement of light.

Hence Kepler says very beautifully: "Certum est vel in retinâ caussâ picturæ, vel in spiritibus caussâ impressionis, exsistere dilatationem lucidorum."—Paralip. in Vitellionem, p. 220. Scherfer expresses a similar conjecture.—[Note A].

[19.]

However this may be, both impressions derived from such objects remain in the organ itself, and last for some time, even when the external cause is removed. In ordinary experience we scarcely notice this, for objects are seldom presented to us which are very strongly relieved from each other, and we avoid looking at those appearances that dazzle the sight. In glancing from one object to another, the succession of images appears to us distinct; we are not aware that some portion of the impression derived from the object first contemplated passes to that which is next looked at.

[20.]

If in the morning, on waking, when the eye is very susceptible, we look intently at the bars of a window relieved against the dawning sky, and then shut our eyes or look towards a totally dark place, we shall see a dark cross on a light ground before us for some time.

[21.]

Every image occupies a certain space on the retina, and of course a greater or less space in proportion as the object is seen near or at a distance. If we shut the eyes immediately after looking at the sun we shall be surprised to find how small the image it leaves appears.

[22.]

If, on the other hand, we turn the open eye towards the side of a room, and consider the visionary image in relation to other objects, we shall always see it larger in proportion to the distance of the surface on which it is thrown. This is easily explained by the laws of perspective, according to which a small object near covers a great one at a distance.

[23.]

The duration of these visionary impressions varies with the powers or structure of the eye in different individuals, just as the time necessary for the recovery of the tone of the retina varies in passing from brightness to darkness (10): it can be measured by minutes and seconds, indeed much more exactly than it could formerly have been by causing a lighted linstock to revolve rapidly, so as to appear a circle.—[Note B].

[24.]

But the force with which an impinging light impresses the eye is especially worthy of attention. The image of the sun lasts longest; other objects, of various degrees of brightness, leave the traces of their appearance on the eye for a proportionate time.

[25.]

These images disappear by degrees, and diminish at once in distinctness and in size.

[26.]

They are reduced from the contour inwards, and the impression on some persons has been that in square images the angles become gradually blunted till at last a diminished round image floats before the eye.

[27.]

Such an image, when its impression is no more observable, can, immediately after, be again revived on the retina by opening and shutting the eye, thus alternately exciting and resting it.

[28.]

Images may remain on the retina in morbid affections of the eye for fourteen, seventeen minutes, or even longer. This indicates extreme weakness of the organ, its inability to recover itself; while visions of persons or things which are the objects of love or aversion indicate the connexion between sense and thought.

[29.]

If, while the image of the window-bars before mentioned lasts, we look upon a light grey surface, the cross will then appear light and the panes dark. In the first case (20) the image was like the original picture, so that the visionary impression also could continue unchanged; but in the present instance our attention is excited by a contrary effect being produced. Various examples have been given by observers of nature.

[30.]

The scientific men who made observations in the Cordilleras saw a bright appearance round the shadows of their heads on some clouds. This example is a case in point; for, while they fixed their eyes on the dark shadow, and at the same time moved from the spot, the compensatory light image appeared to float round the real dark one. If we look at a black disk on a light grey surface, we shall presently, by changing the direction of the eyes in the slightest degree, see a bright halo floating round the dark circle.

A similar circumstance happened to myself: for while, as I sat in the open air, I was talking to a man who stood at a little distance from me relieved on a grey sky, it appeared to me, as I slightly altered the direction of my eyes, after having for some time looked fixedly at him, that his head was encircled with a dazzling light.

In the same way probably might be explained the circumstance that persons crossing dewy meadows at sunrise see a brightness round each other's heads[2]; the brightness in this case may be also iridescent, as the phenomena of refraction come into the account.

Thus again it has been asserted that the shadows of a balloon thrown on clouds were bordered with bright and somewhat variegated circles.

Beccaria made use of a paper kite in some experiments on electricity. Round this kite appeared a small shining cloud varying in size; the same brightness was even observed round part of the string. Sometimes it disappeared, and if the kite moved faster the light appeared to float to and fro for a few moments on the place before occupied. This appearance, which could not be explained by those who observed it at the time, was the image which the eye retained of the kite relieved as a dark mass on a bright sky; that image being changed into a light mass on a comparatively dark background.

In optical and especially in chromatic experiments, where the observer has to do with bright lights whether colourless or coloured, great care should be taken that the spectrum which the eye retains in consequence of a previous observation does not mix with the succeeding one, and thus affect the distinctness and purity of the impression.

[31.]

These appearances have been explained as follows: That portion of the retina on which the dark cross (29) was impressed is to be considered in a state of repose and susceptibility. On this portion therefore the moderately light surface acted in a more lively manner than on the rest of the retina, which had just been impressed with the light through the panes, and which, having thus been excited by a much stronger brightness, could only view the grey surface as a dark.

[32.]

This mode of explanation appears sufficient for the cases in question, but, in the consideration of phenomena hereafter to be adduced, we are forced to trace the effects to higher sources.

[33.]

The eye after sleep exhibits its vital elasticity more especially by its tendency to alternate its impressions, which in the simplest form change from dark to light, and from light to dark. The eye cannot for a moment remain in a particular state determined by the object it looks upon. On the contrary, it is forced to a sort of opposition, which, in contrasting extreme with extreme, intermediate degree with intermediate degree, at the same time combines these opposite impressions, and thus ever tends to a whole, whether the impressions are successive, or simultaneous and confined to one image.

[34.]

Perhaps the peculiarly grateful sensation which we experience in looking at the skilfully treated chiaro-scuro of colourless pictures and similar works of art arises chiefly from the simultaneous impression of a whole, which by the organ itself is sought, rather than arrived at, in succession, and which, whatever may be the result, can never be arrested.

[1] [Plate 1]. fig. 1.

[2] See the Life of Benvenuto Cellini, vol. i. p. 453. Milan edition, 1806.—T.

[III.]

GREY SURFACES AND OBJECTS.

[35.]

A moderate light is essential to many chromatic experiments. This can be presently obtained by surfaces more or less grey, and thus we have at once to make ourselves acquainted with this simplest kind of middle tint, with regard to which it is hardly necessary to observe, that in many cases a white surface in shadow, or in a low light, may be considered equivalent to a grey.

[36.]

Since a grey surface is intermediate between brightness and darkness, it admits of our illustrating a phenomenon before described (29) by an easy experiment.

[37.]

Let a black object be held before a grey surface, and let the spectator, after looking steadfastly at it, keep his eyes unmoved while it is taken away: the space it occupied appears much lighter. Let a white object be held up in the same manner: on taking it away the space it occupied will appear much darker than the rest of the surface. Let the spectator in both cases turn his eyes this way and that on the surface, the visionary images will move in like manner.

[38.]

A grey object on a black ground appears much brighter than the same object on a white ground. If both comparisons are seen together the spectator can hardly persuade himself that the two greys are identical. We believe this again to be a proof of the great excitability of the retina, and of the silent resistance which every vital principle is forced to exhibit when any definite or immutable state is presented to it. Thus inspiration already presupposes expiration; thus every systole its diastole. It is the universal formula of life which manifests itself in this as in all other cases. When darkness is presented to the eye it demands brightness, and vice versâ: it shows its vital energy, its fitness to receive the impression of the object, precisely by spontaneously tending to an opposite state.

[IV.]

DAZZLING COLOURLESS OBJECTS.

[39.]

If we look at a dazzling, altogether colourless object, it makes a strong lasting impression, and its after-vision is accompanied by an appearance of colour.

[40.]

Let a room be made as dark as possible; let there be a circular opening in the window-shutter about three inches in diameter, which may be closed or not at pleasure. The sun being suffered to shine through this on a white surface, let the spectator from some little distance fix his eyes on the bright circle thus admitted. The hole being then closed, let him look towards the darkest part of the room; a circular image will now be seen to float before him. The middle of this circle will appear bright, colourless, or somewhat yellow, but the border will at the same moment appear red.

After a time this red, increasing towards the centre, covers the whole circle, and at last the bright central point. No sooner, however, is the whole circle red than the edge begins to be blue, and the blue gradually encroaches inwards on the red. When the whole is blue the edge becomes dark and colourless. This darker edge again slowly encroaches on the blue till the whole circle appears colourless. The image then becomes gradually fainter, and at the same time diminishes in size. Here again we see how the retina recovers itself by a succession of vibrations after the powerful external impression it received. ([25], [26].)

[41.]

By several repetitions similar in result, I found the comparative duration of these appearances in my own case to be as follows:—

I looked on the bright circle five seconds, and then, having closed the aperture, saw the coloured visionary circle floating before me. After thirteen seconds it was altogether red; twenty-nine seconds next elapsed till the whole was blue, and forty-eight seconds till it appeared colourless. By shutting and opening the eye I constantly revived the image, so that it did not quite disappear till seven minutes had elapsed.

Future observers may find these periods shorter or longer as their eyes may be stronger or weaker ([23]), but it would be very remarkable if, notwithstanding such variations, a corresponding proportion as to relative duration should be found to exist.

[42.]

But this remarkable phenomenon no sooner excites our attention than we observe a new modification of it.

If we receive the impression of the bright circle as before, and then look on a light grey surface in a moderately lighted room, an image again floats before us; but in this instance a dark one: by degrees it is encircled by a green border that gradually spreads inwards over the whole circle, as the red did in the former instance. As soon as this has taken place a dingy yellow appears, and, filling the space as the blue did before, is finally lost in a negative shade.

[43.]

These two experiments may be combined by placing a black and a white plane surface next each other in a moderately lighted room, and then looking alternately on one and the other as long as the impression of the light circle lasts: the spectator will then perceive at first a red and green image alternately, and afterwards the other changes. After a little practice the two opposite colours may be perceived at once, by causing the floating image to fall on the junction of the two planes. This can be more conveniently done if the planes are at some distance, for the spectrum then appears larger.

[44.]

I happened to be in a forge towards evening at the moment when a glowing mass of iron was placed on the anvil; I had fixed my eyes steadfastly on it, and, turning round, I looked accidentally into an open coal-shed: a large red image now floated before my eyes, and, as I turned them from the dark opening to the light boards of which the shed was constructed, the image appeared half green, half red, according as it had a lighter or darker ground behind it. I did not at that time take notice of the subsequent changes of this appearance.

[45.]

The after-vision occasioned by a total dazzling of the retina corresponds with that of a circumscribed bright object. The red colour seen by persons who are dazzled with snow belongs to this class of phenomena, as well as the singularly beautiful green colour which dark objects seem to wear after looking long on white paper in the sun. The details of such experiments may be investigated hereafter by those whose young eyes are capable of enduring such trials further for the sake of science.

[46.]

With these examples we may also class the black letters which in the evening light appear red. Perhaps we might insert under the same category the story that drops of blood appeared on the table at which Henry IV. of France had seated himself with the Duc de Guise to play at dice.

[V.]

COLOURED OBJECTS.

[47.]

We have hitherto seen the physiological colours displayed in the after-vision of colourless bright objects, and also in the after-vision of general colourless brightness; we shall now find analogous appearances if a given colour be presented to the eye: in considering this, all that has been hitherto detailed must be present to our recollection.

[48.]

The impression of coloured objects remains in the eye like that of colourless ones, but in this case the energy of the retina, stimulated as it is to produce the opposite colour, will be more apparent.

[49.]

Let a small piece of bright-coloured paper or silk stuff be held before a moderately lighted white surface; let the observer look steadfastly on the small coloured object, and let it be taken away after a time while his eyes remain unmoved; the spectrum of another colour will then be visible on the white plane. The coloured paper may be also left in its place while the eye is directed to another part of the white plane; the same spectrum will be visible there too, for it arises from an image which now belongs to the eye.

[50.]

In order at once to see what colour will be evoked by this contrast, the chromatic circle[1] may be referred to. The colours are here arranged in a general way according to the natural order, and the arrangement will be found to be directly applicable in the present case; for the colours diametrically opposed to each other in this diagram are those which reciprocally evoke each other in the eye. Thus, yellow demands purple; orange, blue; red, green; and vice versâ: thus again all intermediate gradations reciprocally evoke each other; the simpler colour demanding the compound, and vice versâ.—[Note C].

[51.]

The cases here under consideration occur oftener than we are aware in ordinary life; indeed, an attentive observer sees these appearances everywhere, while, on the other hand, the uninstructed, like our predecessors, consider them as temporary visual defects, sometimes even as symptoms of disorders in the eye, thus exciting serious apprehensions. A few remarkable instances may here be inserted.

[52.]

I had entered an inn towards evening, and, as a well-favoured girl, with a brilliantly fair complexion, black hair, and a scarlet bodice, came into the room, I looked attentively at her as she stood before me at some distance in half shadow. As she presently afterwards turned away, I saw on the white wall, which was now before me, a black face surrounded with a bright light, while the dress of the perfectly distinct figure appeared of a beautiful sea-green.

[53.]

Among the materials for optical experiments, there are portraits with colours and shadows exactly opposite to the appearance of nature. The spectator, after having looked at one of these for a time, will see the visionary figure tolerably true to nature. This is conformable to the same principles, and consistent with experience, for, in the former instance, a negress with a white head-dress would have given me a white face surrounded with black. In the case of the painted figures, however, which are commonly small, the parts are not distinguishable by every one in the after-image.

[54.]

A phenomenon which has before excited attention among the observers of nature is to be attributed, I am persuaded, to the same cause.

It has been stated that certain flowers, towards evening in summer, coruscate, become phosphorescent, or emit a momentary light. Some persons have described their observation of this minutely. I had often endeavoured to witness it myself, and had even resorted to artificial contrivances to produce it.

On the 19th of June, 1799, late in the evening, when the twilight was deepening into a clear night, as I was walking up and down the garden with a friend, we very distinctly observed a flame-like appearance near the oriental poppy, the flowers of which are remarkable for their powerful red colour. We approached the place and looked attentively at the flowers, but could perceive nothing further, till at last, by passing and repassing repeatedly, while we looked sideways on them, we succeeded in renewing the appearance as often as we pleased. It proved to be a physiological phenomenon, such as others we have described, and the apparent coruscation was nothing but the spectrum of the flower in the compensatory blue-green colour.

In looking directly at a flower the image is not produced, but it appears immediately as the direction of the eye is altered. Again, by looking sideways on the object, a double image is seen for a moment, for the spectrum then appears near and on the real object.

The twilight accounts for the eye being in a perfect state of repose, and thus very susceptible, and the colour of the poppy is sufficiently powerful in the summer twilight of the longest days to act with full effect and produce a compensatory image. I have no doubt these appearances might be reduced to experiment, and the same effect produced by pieces of coloured paper. Those who wish to take the most effectual means for observing the appearance in nature—suppose in a garden—should fix the eyes on the bright flowers selected for the purpose, and, immediately after, look on the gravel path. This will be seen studded with spots of the opposite colour. The experiment is practicable on a cloudy day, and even in the brightest sunshine, for the sun-light, by enhancing the brilliancy of the flower, renders it fit to produce the compensatory colour sufficiently distinct to be perceptible even in a bright light. Thus, peonies produce beautiful green, marigolds vivid blue spectra.

[55.]

As the opposite colour is produced by a constant law in experiments with coloured objects on portions of the retina, so the same effect takes place when the whole retina is impressed with a single colour. We may convince ourselves of this by means of coloured glasses. If we look long through a blue pane of glass, everything will afterwards appear in sunshine to the naked eye, even if the sky is grey and the scene colourless. In like manner, in taking off green spectacles, we see all objects in a red light. Every decided colour does a certain violence to the eye, and forces the organ to opposition.

[56.]

We have hitherto seen the opposite colours producing each other successively on the retina: it now remains to show by experiment that the same effects can exist simultaneously. If a coloured object impinges on one part of the retina, the remaining portion at the same moment has a tendency to produce the compensatory colour. To pursue a former experiment, if we look on a yellow piece of paper placed on a white surface, the remaining part of the organ has already a tendency to produce a purple hue on the colourless surface: in this case the small portion of yellow is not powerful enough to produce this appearance distinctly, but, if a white paper is placed on a yellow wall, we shall see the white tinged with a purple hue.

[57.]

Although this experiment may be made with any colours, yet red and green are particularly recommended for it, because these colours seem powerfully to evoke each other. Numerous instances occur in daily experience. If a green paper is seen through striped or flowered muslin, the stripes or flowers will appear reddish. A grey building seen through green pallisades appears in like manner reddish. A modification of this tint in the agitated sea is also a compensatory colour: the light side of the waves appears green in its own colour, and the shadowed side is tinged with the opposite hue. The different direction of the waves with reference to the eye produces the same effect. Objects seen through an opening in a red or green curtain appear to wear the opposite hue. These appearances will present themselves to the attentive observer on all occasions, even to an unpleasant degree.

[58.]

Having made ourselves acquainted with the simultaneous exhibition of these effects in direct cases, we shall find that we can also observe them by indirect means. If we place a piece of paper of a bright orange colour on the white surface, we shall, after looking intently at it, scarcely perceive the compensatory colour on the rest of the surface: but when we take the orange paper away, and when the blue spectrum appears in its place, immediately as this spectrum becomes fully apparent, the rest of the surface will be overspread, as if by a flash, with a reddish-yellow light, thus exhibiting to the spectator in a lively manner the productive energy of the organ, in constant conformity with the same law.

[59.]

As the compensatory colours easily appear, where they do not exist in nature, near and after the original opposite ones, so they are rendered more intense where they happen to mix with a similar real hue. In a court which was paved with grey limestone flags, between which grass had grown, the grass appeared of an extremely beautiful green when the evening clouds threw a scarcely perceptible reddish light on the pavement. In an opposite case we find, in walking through meadows, where we see scarcely anything but green, the stems of trees and the roads often gleam with a reddish hue. This tone is not uncommon in the works of landscape painters, especially those who practice in water-colours: they probably see it in nature, and thus, unconsciously imitating it, their colouring is criticised as unnatural.

[60.]

These phenomena are of the greatest importance, since they direct our attention to the laws of vision, and are a necessary preparation for future observations on colours. They show that the eye especially demands completeness, and seeks to eke out the colorific circle in itself. The purple or violet colour suggested by yellow contains red and blue; orange, which responds to blue, is composed of yellow and red; green, uniting blue and yellow, demands red; and so through all gradations of the most complicated combinations. That we are compelled in this case to assume three leading colours has been already remarked by other observers.

[61.]

When in this completeness the elements of which it is composed are still appreciable by the eye, the result is justly called harmony. We shall subsequently endeavour to show how the theory of the harmony of colours may be deduced from these phenomena, and how, simply through these qualities, colours may be capable of being applied to æsthetic purposes. This will be shown when we have gone through the whole circle of our observations, returning to the point from which we started.

[1] [Plate 1], fig. 3.

[VI.]

COLOURED SHADOWS.

[62.]

Before, however, we proceed further, we have yet to observe some very remarkable cases of the vivacity with which the suggested colours appear in the neighbourhood of others: we allude to coloured shadows. To arrive at these we first turn our attention to shadows that are colourless or negative.

[63.]

A shadow cast by the sun, in its full brightness, on a white surface, gives us no impression of colour; it appears black, or, if a contrary light (here assumed to differ only in degree) can act upon it, it is only weaker, half-lighted, grey.

[64.]

Two conditions are necessary for the existence of coloured shadows: first, that the principal light tinge the white surface with some hue; secondly, that a contrary light illumine to a certain extent the cast shadow.

[65.]

Let a short, lighted candle be placed at twilight on a sheet of white paper. Between it and the declining daylight let a pencil be placed upright, so that its shadow thrown by the candle may be lighted, but not overcome, by the weak daylight: the shadow will appear of the most beautiful blue.

[66.]

That this shadow is blue is immediately evident; but we can only persuade ourselves by some attention that the white paper acts as a reddish yellow, by means of which the complemental blue is excited in the eye.—[Note D].

[67.]

In all coloured shadows, therefore, we must presuppose a colour excited or suggested by the hue of the surface on which the shadow is thrown. This may be easily found to be the case by attentive consideration, but we may convince ourselves at once by the following experiment.

[68.]

Place two candles at night opposite each other on a white surface; hold a thin rod between them upright, so that two shadows be cast by it; take a coloured glass and hold it before one of the lights, so that the white paper appear coloured; at the same moment the shadow cast by the coloured light and slightly illumined by the colourless one will exhibit the complemental hue.

[69.]

An important consideration suggests itself here, to which we shall frequently have occasion to return. Colour itself is a degree of darkness σκιερόν; hence Kircher is perfectly right in calling it lumen opacatum. As it is allied to shadow, so it combines readily with it; it appears to us readily in and by means of shadow the moment a suggesting cause presents itself. We could not refrain from adverting at once to a fact which we propose to trace and develop hereafter.—[Note E].

[70.]