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- Herausgeber: DigiCat
- Kategorie: Geisteswissenschaft
- Sprache: Englisch
In "The Colour-Sense: Its Origin and Development," Grant Allen delves into the complex interplay between human perception of color and the evolutionary underpinnings of this sensory experience. Employing a blend of scientific inquiry and philosophical reflection, Allen examines how color perception has evolved alongside human development, drawing upon a range of disciplines including psychology, physiology, and art. His analytical yet accessible prose invites readers to consider not only the mechanics of color vision but also its profound implications for culture and creativity, situating the work within the late 19th-century discourse on sensory perception and aesthetic experience. Grant Allen, a prominent figure in the fields of science and literature during the Victorian era, possessed a keen interest in the intersections of these domains, reflected in his diverse writings. His background in natural science and his position as a popular science writer provided him with a unique perspective on the intricacies of human perception, leading him to explore the origins of color sense in an era marked by rapid advancements in science and technology. Allen's work often sought to bridge the gap between empirical research and everyday experience, making complex ideas relatable to a broader audience. "The Colour-Sense" is highly recommended for readers interested in the science of perception, aesthetics, or the philosophical implications of sensory experiences. Allen's engaging narrative style not only elucidates the nuances of color perception but also encourages readers to reflect on the significance of colors in their own lives. This thoughtful exploration is sure to resonate with anyone curious about the intersections of science, art, and human experience. In this enriched edition, we have carefully created added value for your reading experience: - A succinct Introduction situates the work's timeless appeal and themes. - The Synopsis outlines the central plot, highlighting key developments without spoiling critical twists. - A detailed Historical Context immerses you in the era's events and influences that shaped the writing. - A thorough Analysis dissects symbols, motifs, and character arcs to unearth underlying meanings. - Reflection questions prompt you to engage personally with the work's messages, connecting them to modern life. - Hand‐picked Memorable Quotes shine a spotlight on moments of literary brilliance. - Interactive footnotes clarify unusual references, historical allusions, and archaic phrases for an effortless, more informed read.
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Veröffentlichungsjahr: 2022
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The Colour-Sense: Its Origin and Development
Table of Contents
Introduction
In this inquiry into how living beings came to see, to signal, and to desire through color, The Colour-Sense: Its Origin and Development turns the friction between biological necessity and aesthetic delight into a guiding question about what nature builds and what the mind makes of it, asking how perception that serves survival can also become a source of pleasure, taste, and meaning across species and human cultures, and how the visual world’s material forces and the observer’s evolving faculties meet to produce the sensuous, patterned, and purposeful phenomena we recognize as the colour-sense.
Grant Allen’s book belongs to Victorian science writing, a genre that brought new theories to a wide audience with argumentative clarity and illustrative examples. First appearing in the late nineteenth century amid the intense post-Darwin debates about evolution, heredity, and mind, it examines colour perception within the intellectual setting of natural history and comparative psychology. Allen, known for both fiction and popular science, approaches the topic as a synthesizer of contemporary research rather than as a laboratory specialist. The result is a work that treats the colour-sense as an evolutionary problem, grounded in observation, analogy, and careful reasoning for general readers.
Without presuming technical training, the book unfolds as a sustained argument: it surveys colour in the natural world and human making to trace possible pathways by which perception and preference could have developed. The voice is lucid, assured, and inquisitive, using concrete instances to test general principles and to refine them rather than to dazzle. Allen patiently defines terms, weighs alternative explanations, and builds cumulative cases that invite the reader’s participation. The tone balances scientific caution with imaginative reach, offering a reading experience that feels like a guided tour through a gallery of natural phenomena where each exhibit is asked to explain itself.
Several persistent themes give the work its coherence. Colour is treated as both signal and sensation, locating it at the intersection of organism and environment. The argument is framed against ideas widely discussed in nineteenth-century evolutionary thought, including selection, adaptation in display and concealment, and the communicative uses of pattern. It also probes how attention, memory, and habit might consolidate a taste for certain visual contrasts or harmonies. Throughout, the emphasis falls on gradual development rather than abrupt invention, encouraging readers to see complex perception emerging from small adjustments that confer advantage and accumulate over time.
For contemporary readers, the book matters because it models a way of linking biology, psychology, and aesthetics without reducing any one to the others. Questions about how environments shape perception, and how perception in turn shapes behavior and culture, remain central to cognitive science, ecology, design, and the study of media. Allen’s attention to function and form suggests practical resonances with visual communication, art, and technology, where colour continues to guide choice, signal risk, and organize information. By treating pleasure and utility as intertwined, the work anticipates ongoing debates about embodiment, adaptation, and the sources of aesthetic judgment.
Reading The Colour-Sense today also invites reflection on the history of ideas. As a product of its era, the book occasionally uses categories and examples that reflect Victorian conventions, yet its core project—to explain a striking feature of experience by tracing its development—retains clarity and force. Readers may wish to dialogue with more recent research in vision science and evolutionary theory as they go, noting where contemporary evidence corroborates, revises, or complicates earlier claims. Such engagement enhances the text’s vitality, emphasizing its role as a catalyst for inquiry rather than a static compendium of settled answers.
Approached in this light, The Colour-Sense offers both an argument and an attitude: a disciplined curiosity about how the living world produces richness from utility. Its pages encourage patience with evidence, sympathy for competing hypotheses, and delight in connections that cross species and domains. By following Allen’s patient exposition, readers encounter a portrait of perception as an evolving relationship, not a fixed faculty, and they emerge better equipped to ask productive questions about design, taste, and communication. The enduring appeal lies in its promise that careful observation and bold synthesis can illuminate how colour became one of life’s most expressive languages.
Synopsis
The Colour-Sense: Its Origin and Development (1879) by Grant Allen proposes to trace the emergence of human and animal sensitivity to color through evolutionary history and cultural change. Framed as an essay in comparative psychology, it gathers evidence from physiology, natural history, botany, linguistics, and the arts to argue for a gradual, adaptive growth of chromatic perception out of simpler visual capacities. Allen’s opening chapters set the question: what selective forces first made color distinctions advantageous, and how might those pressures be read in living forms and human practices? He outlines a program linking mind and environment, signal and receiver, sensation and use.
He begins with the eye and the measurable facts of sensation. Distinguishing brightness from hue, and saturation from tint, Allen sketches contemporary theories of color vision and the anatomy of retinal elements responsible for chromatic response. He treats color sensitivity as superimposed on earlier light-and-shade perception, with gradations of fineness and range among species. Psychophysical data and everyday illusions serve to show that perceived color depends on context and contrast as much as on stimulus. This physiological groundwork supports his larger claim: before color can affect behavior or selection, it must first be detectably registered by an organism’s nervous system.
From this base, Allen surveys animals to reconstruct plausible stages in the evolution of color discrimination. He points to phototropic responses and simple light-sense in lower forms, then to more elaborate color-guided behaviors in insects and birds. Utility and ornament intertwine: color enables foraging among blossoms, species recognition, and mate choice. Sexual selection enters as a recurrent factor, with bright plumage and displays interpreted as signals calibrated to conspecific vision. He emphasizes reciprocity between visibility and viewer, presenting courtship apparatus, territorial badges, and diurnal habits as contexts in which a refined colour-sense would be strongly favored and consequently elaborated.
Turning to plants, he argues that vegetation does not merely present color passively; it harnesses animal vision. Flower hues, markings, and contrasting patterns are read as adaptations for pollinator attention, while the conspicuous ripening of fruits serves seed dispersal by visually guided animals. Seasonal changes and background foliage create the fields against which such signals must be legible. By correlating pigment distribution with pollination syndromes and dispersal modes, Allen proposes a coevolutionary dialogue: as animals better distinguish chromatic cues, plants evolve clearer invitations and warnings. Color thus becomes a currency of ecological communication linking disparate kingdoms.
Allen then considers concealment, mimicry, and conspicuous warning as complementary strategies that further reveal how color shapes and is shaped by vision. Camouflage aligns animal surfaces with substrates and light, increasing survival where predators are sight-hunters. Mimetic resemblances and startling contrasts indicate that receivers’ perceptual habits impose exacting tests on would-be deceivers or advertisers. In sexual displays, by contrast, excess visibility is cultivated under mate choice. These cases collectively suggest that perception and coloration evolve in tandem, refining thresholds, contrasts, and preferences. The pattern, he argues, is consistent across taxa, even as the particular palettes and tactics differ.
Human colour-sense is treated both biologically and historically. Allen discusses variation in color discrimination, including color-blindness, and the developmental trajectory by which children learn to sort and name hues. He brings in linguistic and literary testimony to show that societies differ in the number and boundaries of color terms, and that historical texts sometimes organize colors unlike modern usage. Decorative arts, dress, and industry provide further indices of taste and capacity, revealing how technology and commerce expand available pigments and combinations. Across these materials, he treats cultural patterning not as a denial of biology, but as its expression in changing conditions.
The essay concludes by reassembling these strands into a general evolutionary account of color as a functional sense with wide consequences. Without claiming finality, Allen offers a schematic history in which perception, signaling, and environment co-adjust through selection, gradually widening both the spectrum attended to and the purposes it serves. The work’s resonance lies in its interdisciplinary reach: it models how psychology can be grounded in natural history while remaining attentive to language and art. As a Victorian synthesis, it frames enduring questions about how minds meet worlds, inviting later inquiry to refine mechanisms without abandoning the comparative vision.
Historical Context
Grant Allen’s The Colour-Sense: Its Origin and Development appeared in 1879, in late-Victorian Britain, when scientific naturalism shaped debates in universities, learned societies, and periodicals. The Royal Society, the Royal Institution, and the British Association for the Advancement of Science promoted experimental method and public discussion. Charles Darwin’s ideas, from On the Origin of Species (1859) to The Descent of Man (1871), had redirected inquiry toward the evolutionary origins of human faculties. In the same year, Wilhelm Wundt opened his psychological laboratory at Leipzig (1879), signaling a new discipline concerned with sensation. Allen’s book entered this milieu, linking color perception to evolutionary history.
Allen, a Canadian-born British writer educated at King Edward’s School, Birmingham, and Merton College, Oxford, moved through academic and colonial institutions before settling in London’s literary-scientific world. In the early 1870s he taught mental and moral philosophy at the government college in Spanish Town, Jamaica, an experience that sharpened his interest in comparative psychology. Returning to Britain, he wrote for journals such as the Fortnightly Review and developed a close intellectual affinity with Herbert Spencer’s evolutionary psychology. His Physiological Aesthetics (1877) prepared readers for The Colour-Sense by arguing that aesthetic response arises from nerve physiology shaped by evolution, a program he advanced with greater focus in 1879.
After 1859, naturalists increasingly treated color in nature as evidence for selection. Alfred Russel Wallace emphasized protective coloration and warning displays, while Henry Walter Bates’s 1862 study of Amazonian butterflies popularized mimicry as an adaptation. Darwin’s Descent of Man (1871) proposed that sexual selection, including mate choice for brilliant plumage or ornament, helped explain animal coloration. The 1870s saw exchanges over the relative weight of natural versus sexual selection in producing color patterns, culminating in Wallace’s essays in Tropical Nature (1878). Allen’s book synthesizes these discussions, applying evolutionary reasoning to the human sense of color and to aesthetic preference without abandoning empirical caution.
Mid-century physiology provided a technical framework for Allen’s claims. Thomas Young’s early trichromatic hypothesis gained experimental support in the work of Hermann von Helmholtz, whose optics and color-matching experiments elaborated three-receptor theory. James Clerk Maxwell’s colorimeter studies and his 1861 additive synthesis of a color photograph demonstrated measurable laws of mixture. In 1878, Ewald Hering advanced an opponent-process account of color sensation, provoking debate over the mechanisms of hue and contrast. British and German laboratories refined instruments and vocabulary for visual science, allowing writers like Allen to connect evolutionary conjectures with concrete findings about retinal receptors, neural pathways, and perceptual contrast.
The book also emerged alongside psychophysics and the institutional birth of psychology. Gustav Fechner’s Elements of Psychophysics (1860) quantified the relation between stimulus and sensation, and F. C. Donders’s reaction-time experiments (1860s) modeled mental processing as measurable. Wilhelm Wundt’s Leipzig laboratory (1879) organized training, instruments, and journals that privileged experimental methods for studying sensation and attention. British discussions by Alexander Bain and Herbert Spencer linked habit, nerve energy, and adaptation, framing perception as a product of use and environment. Allen wrote into this conversation, translating technical results about thresholds, contrast, and association into evolutionary arguments about how color discrimination could have developed.
Industrial modernity made color a practical concern. William Henry Perkin’s discovery of mauveine (1856) initiated a British and German synthetic-dye industry that transformed textiles, printing, and consumer taste. Chromolithography and illustrated journalism spread vivid palettes to mass audiences. At the same time, transport and signaling systems depended on reliable color recognition. John Dalton’s 1798 account of his own color blindness and George Wilson’s Researches on Colour-Blindness (1855) framed the issue scientifically, while Frithiof Holmgren’s wool test (1870s), publicized after the 1875 Lagerlunda railway accident in Sweden, spurred systematic screening. Allen’s discussion positioned color sense within these technological and safety controversies.
Victorian philology and anthropology supplied another strand. William Ewart Gladstone argued, in his Homeric studies (1858–1865), that ancient Greek colour vocabulary was limited, a claim elaborated by Lazarus Geiger, who tied linguistic development to stages of perception. Ethnographers and travelers, working through imperial networks and societies such as the Royal Geographical Society, circulated observations on colour naming and decoration in non-European cultures. Museum collections in London and provincial cities assembled specimens illustrating protective and display coloration. Allen drew on these comparative materials, while emphasizing testable mechanisms, to chart how human colour discrimination and preference could be historically situated without detaching them from biology.
As a synthesis, The Colour-Sense mirrors late-Victorian confidence in explaining mind and art through natural history and laboratory findings, yet it also registers the era’s disputes—between trichromatic and opponent theories, or between sexual and natural selection. The book’s reliance on experiments, comparative observation, and cross-disciplinary citation reflects the institutions that fostered them: learned societies, expanding laboratories, and global collecting networks. Its attention to industrial dyes, signaling, and color blindness addresses contemporary practical stakes. By grounding aesthetic response and perception in evolution and physiology, Allen critiqued transcendental accounts of beauty and advanced a characteristically nineteenth-century program: to naturalize culture without trivializing it.
The Colour-Sense: Its Origin and Development
BOSTON:HOUGHTON, OSGOOD, & COMPANY. 1879.
PREFACE.
The materials which form the nucleus of the present volume were originally collected as part of the basis for a chapter on “the Genesis of Æsthetics” in my little work on “Physiological Æsthetics,” published some two years since. I found, however, when I came to arrange them, that the subject had grown under my hands, and that it would be impossible fully to develop my ideas except in the form of a separate treatise. The omission seemed all the more desirable, because my former work dealt only with Æsthetics as an element of human psychology: while the materials here collected refer rather to the wider science which studies the phenomena of mind throughout the whole animal world. Accordingly, I deferred their publication for the time, only mentioning my original intention in a footnote on p. 156 of “Physiological Æsthetics.” But most of the critics who kindly noticed that little work were so unanimous in calling attention to the hints which I had thrown out with reference to the Colour-Sense, and the love for colour which forms such a striking characteristic of mankind, that I determined on following up the subject on a wider basis, and elucidating my view by full inductive generalisations. The present volume is the result.
Meanwhile two works appeared, in Germany and in England, which necessitated considerable divergences from my original plan. The first was Dr. Hugo Magnus’s “Geschichtliche Entwickelung des Farbensinnes[1];” the second Mr. A. R. Wallace’s “Tropical Nature.” Put shortly, the gist of my theory was this: that the taste for bright colours has been derived by man from his frugivorous ancestors, who acquired it by exercise of their sense of vision upon bright-coloured food-stuffs; that the same taste was shared by all flower-feeding or fruit-eating animals; and that it was manifested in the sexual selection of brilliant mates, as well as in other secondary modes, such as the various human arts. The two volumes mentioned above came like utterly destructive criticisms of any such belief. Dr. Magnus endeavoured to prove that the Colour-Sense of mankind was a late historical acquisition of the race, whose beginnings hardly dated back as far as the Homeric and Vaidik periods. Mr. Wallace controverted, with all his well-known vigour and ingenuity, the theory of sexual selection, first announced by Mr. Darwin, upon which rested almost the whole argument for a love of pure colour among the lower animals. Thus these two books between them cut away the whole ground from under my feet. It became necessary to go back over my materials afresh, and to seek for evidence against both anticipatory assailants. I have tried, therefore, to show, in opposition to Dr. Magnus, that the Colour-Sense of mankind dates back to the earliest appearance of our race upon earth; and, in opposition to Mr. Wallace, that a modified form of the sexual selection theory may still survive his powerful attack. I am aware how ill prepared I am to encounter so thorough a biologist as the joint discoverer of Natural Selection on his own ground; but I have humbly offered such arguments as lay in my power, trusting to the generosity of my opponent to forgive any technical errors which may easily creep into a discussion of the sort.
I should like to add that I enter the lists as a comparative psychologist, not as a biological student. I do not pretend to discover facts of botany or zoology at first hand: I accept them as data from the lips of competent specialists. Yet I hope my work may prove valuable in its own peculiar sphere, which ought to be kept distinct from the objective biological sciences whose conclusions form its basis. Our great naturalists supply us with the facts upon which to build our comparative psychology: and I hope there is no presumption in employing them sometimes to test the logical correctness of a few among the naturalists’ own conclusions.
One of the main necessities of science at the present day is the existence of that organising class whose want was pointed out by Comte, and has been further noted by Mr. Herbert Spencer. To this class I would aspire, in a humble capacity, to belong. But the organising student cannot also himself be a specialist in all the sciences whose results he endeavours to co-ordinate: and he must, therefore, depend for his data upon the original work of others. If specialists find technical errors in such co-ordinated results, they should point them out frankly for correction and improvement, but they should not regard them as fit subjects for carping criticism. I shall feel grateful to any biologists who can suggest alterations or modifications in any part of what I cannot but feel a very tentative and rudimentary work. But unless we make a beginning in psychology we shall never reach the end: and I send forth my speculations rather in the hope that they may arouse comment and lead to further researches, than because I consider them in any way final or complete.
With regard to the authorities used or quoted, I have followed the plan of making no references to original works when dealing with the accepted common-places of science; but wherever I have occasion to note a particular fact, of comparatively modern ascertainment or specialist knowledge, I give the authority in a footnote. For the general groundwork of my theory, my acknowledgments are mainly due to the works of Mr. Darwin and Mr. Herbert Spencer, which I seldom quote by name, because they now form part of the established body of scientific doctrine. After these, I owe most to Mr. A. R. Wallace, Mr. Bates, and Mr. Belt. For personal assistance, by letter or otherwise, I must thank Mr. Darwin, who supplied me with corrections on the colours of flowers; Mr. Wallace, who kindly wrote to me with regard to the colours of fruits; Mr. Galton, F.R.S., for an introduction to the library of the Royal Society; Mr. Gladstone, who called my attention to notes in German periodicals; the Rev. A. H. Sayce, for reference to Assyrian and Babylonian works of art; the Rev. T. K. Cheyne, for aid on the question of Hebrew colour-terms; Mr. H. N. Moseley, naturalist to the Challenger expedition, for references to papers on the colouration of deep-sea organisms; Sir John Lubbock and Mr. B. T. Lowne, for copies of their original researches on the eyes and optical perceptions of insects; and the Rev. S. J. Whitmee of Samoa, with a large number of other missionaries or civil servants, for information with regard to the Colour-Sense of savages.
In a more strictly personal sense, I owe my acknowledgments to my friends, Mr. F. T. Richards of Trinity College, Oxford, Mr. G. J. Romanes, F.L.S., and Professor G. Croom Robertson, for constant assistance in calling my attention to passages in books or periodicals which bore on the subject under investigation.
Finally, I should mention that, although most of the matter contained in the present volume is entirely new, I have incorporated into Chapters IV. and VI. the substance of two papers on “The Origin of Flowers” and “The Origin of Fruits,” which appeared in the “Cornhill Magazine” for May and August 1878. Part of the materials for Chapter X. were also included in a note which I contributed to “Mind” for January of the same year.
G. A.
CHAPTER I.
INTRODUCTORY.
There is no element of our sensuous nature which yields us greater or more varied pleasure than the perception of colour. Whether we look at the larger physical wholes, the azure heaven above us, the purple sea beneath us, and the green meadows by our side;—or at the smaller organic bodies, the brilliant flowers, the crimson foliage of autumn, the gaudily painted butterflies, the beetles clad in burnished gold, the peacock adorned with all the hues of the rainbow, and the humming-birds decked out in ruby, sapphire, and amethyst;—or again at the transient effects of light in the spectrum, the soap-bubble, the iridescent surface of the opal, the tints of eventide mirrored in the glassy lake;—in each and every case we feel a thrill of pure and unselfish enjoyment, which no other mere sensuous stimulation is capable of arousing in our breasts. The pleasure of colour is one which raises itself above the common level of monopolist gratification, and attains to the higher plane of æsthetic delight.
Nor is man the only creature who can appreciate and enjoy the lavish store of beauty which nature pours forth for his pleasure in the fields and the forest. We shall see reason to conclude, from the facts collected in this volume, that many of our dumb relations can fully enter into the love for exquisite colour, at least in its simplest and earliest forms. We shall find good ground for believing that the bird of paradise does not display its gorgeous plumage to the careless eyes of an unobservant mate; that the gaily painted butterfly is not insensible to the lovely tracery upon the wings of its fellow; and even that the tropical lizards or batrachians can duly admire the glistening coats, crimson crests, or golden pouches of their lissome helpmates. We shall further note certain habits which may lead us to suspect that birds and insects are pleasurably affected, not only by the colour of their own kind, but also by the delicate or brilliant tints of the fruits and flowers upon which they feed. In short, our object must be to trace back the pleasure which man experiences from the deft combination of red and green and violet, in painting or in decorative art, to a long line of ante-human ancestry, stretching back indefinitely through geological ages to the first progenitors of vertebrate life.
More than this we must attempt to show. If we would learn fully the whole history of the colour-sense, we must track it backward through the generations of the earlier earth, till we discover what were the circumstances by which it was first produced. We must find out how the various modes of æther-waves, which we now know as colours, came originally to be distinguished from one another by the nascent eyes of half-developed reptiles and insects. We must see by what steps the hues of flowers, and seeds, and fruits, and small animal prey caused the growth of a distinctive colour-perception in the creatures which fed upon them. And we shall probably conclude at the same time that the sense thus developed became in turn a source of new pleasure to its possessors, and a groundwork for more marvellous developments in future. The taste which was formed by the lilies and roses, the golden oranges and purple grapes, ended by producing the metallic lustre of the sun-birds and the daintily shaded ornamentation of the argus-pheasant.
We may hope to show, furthermore, that the existence of bright colouring in the world at large is almost entirely due to the influence of the colour-sense in the animal kingdom. I do not mean, of course, that animals have anything to do with the objective existence of those different æther-waves in the pencil of light which, when decomposed or separated, we perceive as colours; nor do I mean to include in this category the shades of earth, sea, sky, and other great inorganic masses. Obviously the human or animal eye could have no influence upon their origin or colouring. Even the green leaves of the trees and grasses seem quite independent of man or beast. But I still think that a vast mass of the coloured objects with which we are most familiar owe their hues to the perceptions of some insect, bird, or animal. If we look briefly at a few of the best-known cases, the reader will more clearly comprehend the line of argument which this book proposes to itself.
In the drawing-room where we sit, every object has obtained its colour entirely with reference to the likes and fancies of humanity. Not only have the pictures and ornaments been painted so as to please our eyes, but the carpets, the wall-paper, the curtains, the table-covers, the embroidery, the damask on the chairs and sofas, the clothing of the women and children, have all been dyed on purpose to stimulate and gratify the sense of sight. Indeed, there is scarcely an article of human use and manufacture, from the vermilion-stained earthenware of the prehistoric savage and the woad adornment of the Cymric warrior[2], to the Lambeth and Vallauris pottery, or the cretonnes and crewel-work of modern æsthetic designers, which has not received some special manipulation to add pleasing colour by means of dyes or pigments. The universal effect of the colour-sense on human products is too obvious to need further illustration.
A step lower down, we reach the actual bodies of men and animals themselves. It would seem at first sight as though the colour-sense could have nothing to do with the production of these. Yet the theory of sexual selection, into which we shall enter more fully hereafter, shows us how the long-continued choice of beautiful mates may have had the effect of encouraging the growth of bright-hued individuals, and the obsolescence of their less favoured fellows. I shall try to point out, also, an adjunct to this theory, which seems to have escaped even the keen eyes of Mr. Darwin, Mr. Wallace, and their German allies. I shall endeavour to prove that only those animals display beautiful colours, due to sexual selection, in whom a taste for colour has already been aroused by the influence of flowers, fruits, or brilliant insects, their habitual food. As the liking cannot have grown up without some groundwork of advantage to be gained by it, we might gather, even a priori, that such would be the case; and I hope, in the sequel, to adduce a sufficiently large array of positive instances to justify an inductive conclusion to the same effect.
Taking still another step backward, we arrive at the brilliantly coloured fruits and flowers, upon which these tastes were formed. And here we shall have reason to believe that the agency of insects has been most powerful in developing the hues of blossoms; while the fruits, as we shall see, are rather due to the selective action of birds and mammals. Between them almost all the colours of vegetal life, except the uniform green of the foliage, are probably produced, being due to the colour-sense of one or other of the great seeing classes, the vertebrate and the articulate.
Many lesser cases may be alleged, where colours have been acquired for purposes of protection or deception, and of such an abundance will be forthcoming in their proper place. But enough has doubtless been said to show the immense importance of the colour-sense in man or animals, and the conspicuous part which (as I believe) it has played in the moulding of organic forms. If I put in two antithetical paragraphs the various great classes of coloured objects which we do or do not owe to its operation, the reader will be able to see at a glance just how much influence I claim for it.
We do not owe to the colour-sense the existence in nature of the rainbow, the sunset, or the other effects of iridescent light; the blue sky, the green or purple sea, the red rocks, or the other great inanimate masses; the foliage of trees and shrubs, the hues of autumn, and the tints of precious stones or minerals generally.
But we do owe to the colour-sense the beautiful flowers of the meadow and the garden,—roses, lilies, carnations, lilacs, laburnums, violets, primroses, cowslips, and daisies; the exquisite pink of the apple, the peach, the mango, and the cherry, with all the diverse artistic wealth of oranges, strawberries, plums, melons, brambleberries, and pomegranates; the yellow, blue, and melting green of tropical butterflies; the magnificent plumage of the toucan, the macaw, the cardinal-bird, the lory, and the honeysucker; the red breast of our homely robin; the silver or ruddy fur of the ermine, the wolverine, the fox, the squirrel, and the chinchilla; the rosy cheeks and pink lips of English maidens; the whole catalogue of dyes, paints, and pigments; and, last of all, the colours of art in every age and nation, from the red cloth of the South Seas, the lively frescoes of the Egyptian, and the subdued tones of Hellenic painters, to the stained windows of Poitiers and the Madonna of the Sistine Chapel.
The origin and rise of this powerful sense, and the means by which it has effected all these marvellous reactions on the external world, form the text upon which we must string our discourse in the present volume. We shall begin with the nature of colour, viewed as an external and objective fact; we shall next look at the steps by which the various eyes of insects and animals became sensible to its diverse stimulations; we shall then proceed to ask what secondary effects the newly acquired sense produced upon the surrounding existences; and we shall finally examine its remote æsthetic results in the sphere of human activity. We shall thus have traced the perception of colour from its first faint beginnings in palæozoic seas or carboniferous forests down to its latest developments in the palaces or galleries of civilised man.
CHAPTER II.
ÆTHER-WAVES AND THEIR VARIETIES.[1]
Before we can investigate any sensation in men or animals, we must find out what is the external agency to which it corresponds. Every feeling answers to some outer fact, and in the development of life the fact must necessarily have preceded the feeling. Unless there had been matter there could never have been mind[1q]. Without resistance we could not experience touch; without air we could not possess hearing; without æther[3] we could not have developed the wonderful faculty of sight. Organic substances, acted upon by peculiar agencies in the inorganic world, give rise to the phenomena of sensation; but we cannot understand the existence of sensation unless we previously grant the existence of an influence capable of developing it. Idealism, which looks fallaciously plausible when applied to the fully evolved intelligence, becomes meaningless and self-contradictory when applied to the problem of its evolution.
We must begin, then, by allowing that, previous to all perception of colour by men or animals, colour itself existed as an agency in the external universe. The development of the colour-sense is equivalent to the growth of a mechanism by which this agency became capable of affecting organic matter. In the present chapter we will consider the nature of the objective agency, while in the next we shall have to look at the first and rudest form of the percipient mechanism.
Throughout the whole vast ocean of space in which suns, stars, and planets float like inconspicuous islets of light, modern science has taught us that an all-pervading element, known as æther, fills every available interstice. From constellation to constellation of sidereal bodies the æther spreads in wide expanses, which stretch uninterrupted over countless millions of miles. Between atom and atom of terrestrial substances the æther penetrates into tiny intervals whose minuteness the boldest mathematicians have only lately ventured to measure. Where-ever matter is not, æther is. Every sun and every molecule floats in a circumambient matrix of this unknown agent. If we could view the most solid body with a microscopic eye, magnifying some thousands of millions of diameters, we should see that it was composed of innumerable little masses, none of them in actual contact with its neighbours, but all bound to one another, as the earth is to the sun, by their mutual attractions extending over an intervening space. This space would be filled, in the one case as in the other, by the ubiquitous æther. And though we can never succeed in knowing its existence directly, yet we are every moment experiencing its effects in the most obvious and unmistakable manner. Just as we believe in air, which we never see, because we can feel it, so we believe in æther, which we can never handle, because we perpetually see by it and through it.
Æther, though infinitely light and elastic, is naturally a solid, or something very like one. But it shares the common property of other solids in its ability to transmit undulations from a centre of disturbance. We all know that if we set any body in motion, it imparts a portion of its motion to all other bodies with which it comes in contact. So, too, if we set up vibratory movements in a bell, we know that its particles knock up against the air-particles in their neighbourhood, and thereby send off into surrounding space a series of concentric air-waves, which, when they strike the appropriate human organ, are known to us in consciousness as sounds or tones. And inexactly the same way, when disturbances of a peculiar kind affect material particles of any sort, they set up a like series of concentric waves in the circumambient æther, which, falling in turn on their appropriate organs, are recognised in consciousness as heat, light, or colour. What is the exact nature of these waves and their differences we have next to inquire.
Apparently every movement of a material body or particle sets up more or less motion in the surrounding æther. We know now that every sound, every moving energy, every activity of any sort, as it dies away, is transferred by minute friction to the ætherial medium which bathes us on every side. But the stronger class of æther-waves, with which we have now to deal, is originated only in a single way. They all arise from the vibrations of a material body in that state of rapid molecular or atomic motion which we commonly know as red or white heat. The waves thus set up may be reflected, refracted, twisted about, and returned in varying proportions by other surrounding objects, but they all owe their original existence to a heated material mass, whether that mass be the sun, the dog-star[4], the drawing-room fire, or the flame of a candle. So we must look for a moment at the source of such æther-waves before we can comprehend the nature of the waves themselves.
Directly or indirectly, in every case, the vibration of the original heated body is due to the rushing together of masses, molecules, or atoms which were previously in a state of separation. In the heavenly bodies, the sun and the fixed stars, the attraction of gravitation (which affects masses) is drawing together their skirts; and under its influence the outlying matter of their systems is clashing with the central sphere and producing a terrific degree of heat; just as the continued clashing of hammers on an anvil will heat a piece of iron red-hot here on our little earth. In the grate and the candle, again, the attraction of chemical affinity (which affects atoms) is drawing together tiny particles of carbon and oxygen; and as the atoms clash against one another in the embers or the flame, they are put into a similar state of rapid vibration or heat. In physical language, the potential energy of their previous separation has become kinetic in the act of union, and is now being radiated off to surrounding objects. As the quickly vibrating little bodies, either in the sun or the flame, fly from side to side, they impart each second a portion of their moving energy to the æther about them; and each ætherial molecule continues to impart the communicated impulse to adjacent molecules, so that a series of spherical waves is set up in every direction from the central disturbance. If nothing intervenes to prevent them, these waves go on widening and weakening through all space ad infinitum, at least as far as human science or conjecture can follow them.
But all the æther-waves are not of exactly the same size, nor do they follow one another with exactly the same rapidity. When a material body vibrates with a comparatively slight motion (or, as we say in other words, is only slightly heated), the waves to which it gives rise are comparatively slow and voluminous: as the rate of vibration increases, more rapid waves succeed in the surrounding æther; and when the rapidity of vibration becomes very great, the resulting waves follow one another with an almost incredible speed. Three principal varieties of slower or quicker æther-waves are commonly distinguished, according to the effects which they produce upon the human organs.
The slowest undulations are known as heat-waves; those of intermediate rapidity as light-waves; and the quickest of all as chemical waves.
All three classes of waves are produced together by a body in a state of high molecular energy, such as the sun. Fortunately, we are able to separate the various kinds from one another, and to demonstrate their several properties, by means of a simple piece of triangular glass, known as a prism.
If we make a small slit in the shutter of a darkened room, and allow a few of the æther-waves, generated by the sun, to enter through this aperture, we can interpose the prism across their path, and project them sideways on to a screen. When we do so we find that the various waves are all bent upward, but not all equally. They occupy a broad space on the screen, the slowest waves striking the lowest portion, and the quickest falling at the top, while those of intermediate speed hit the middle space.[2] If we put a thermometer of very delicate construction (known as a thermopile[5]) at the lowest point where the waves surge against the screen, we shall find that, in this portion of the wave-bundle, the undulations possess great heating power. If we put a piece of specially prepared paper at the highest point where the weaves alight, we shall similarly find that the undulations of that region possess high chemical power. And if we look at the intermediate space, we shall see for ourselves that the waves of that part produce the greatest amount of light and colour. So here we learn that in every bundle of solar æther-waves these three classes of undulations are closely combined; but by the interposition of a proper medium they can be sifted and separated each into a place of its own.
Fundamentally, then, light and radiant heat are identical. And not only so, but a third order of rays—the chemical—is always bound up with them in the waves which come to us from the sun. Yet though in their objective nature these various agencies are so similar—differing not at all in kind, but only in degree—there is a very strange diversity in our subjective perception of their effects. The slowest æther-waves we perceive with every portion of our bodies, and know as heat; the intermediate æther-waves we perceive through a pair of small and special organs—the eyes—and know as light; while the fastest æther-waves we do not perceive at all, except by very roundabout and indirect means.
The reasons for this difference must surely be very striking ones. It seems curious that such similar agencies should be so diversely cognised, or should escape our cognisance altogether. And it is for the purpose of bringing into clear relief so strange a fact that I have chosen what doubtless seemed at first sight an awkward and unfamiliar mode of envisaging a well-known subject. The question why we have two distinct methods for perceiving two closely allied forms of æther-waves, and no method at all for perceiving the third, is a question which evolutionism is bound to answer before it proceeds to the minor discrimination of those lesser differences known as colours.
For when we look at the matter objectively, we see at once that each colour differs from its neighbour in just the same manner as heat differs from light, though only to a less degree. Accordingly, we must ask first, Why are the senses of animals so differently affected by the extremes and the mean of the solar undulations? And when we have answered that question we may go on to the next, How did the various minor undulations of mean rapidity come to have differential sensations attached to them in consciousness?
