In the case of sexual selection among birds, again, I believe that the gorgeous plumage has its basis of origin in that pre-eminent vitality which Mr. Tylor and Mr. Wallace have insisted on. But, as before indicated, this will not serve to explain its special character for each several species of birds. Here, again, conspicuousness and recognition are unquestionably factors. But that the bright plumage of male birds awakens emotional states in the hens, that it probably also arouses sexual appetence, seems to be shown by the manner in which the finery is displayed by the male before the female. I think it is probable, also, that pleasure, becoming thus associated with bright colours in the mate, is also aroused by bright colours in other associations. Thus the gardener bower-bird, described by Dr. Beccari,[IG] collects in front of its bower flowers and fruits of bright and varied colours. It removes everything unsightly, and strews the ground with moss, among which it places the bright objects from among which the cock bird is said to select daily gifts for his mate's acceptance! Dr. Gould states that certain humming-birds decorate their nests "with the utmost taste," weaving into their structure beautiful pieces of flat lichen. If by crediting birds with a sense of beauty we mean that in them pleasurable emotions may be aroused on sight of objects which we regard as beautiful, I am not prepared to deny them such a sense of beauty, nay, I fully believe that such pleasurable feelings are aroused in them. When, however, it is said that the gorgeous plumage of male birds has been produced by the æsthetic choice of their mates, I am not so ready to agree. A consciously æsthetic motive has not, I believe, been a determining cause. The mate selected has been that which has excited the strongest sexual appetence; his beauty has probably not, as such, been distinctly present to consciousness. Here, then, we have again the question which arose in connection with floral beauty—How is it that the sight of the mates selected by hen birds excites in us, in so many cases, an æsthetic pleasure?
It is clear that this is a matter rather of human than of animal or comparative psychology. As such, except for purposes of illustration, it does not fall within the scope of this work. I can, therefore, say but a few words on the subject. The view that I think erroneous is that either floral beauty or the beauty of secondary sexual characters has been produced on æsthetic grounds, that is to say, for the sake of the beauty they are seen by man to possess. It is, therefore, to the point to draw attention to the fact that many of the objects and scenes which excite in us this æsthetic sense have certainly not been produced for the sake of their beauty. Their beauty is an adjunct, a by-product of rarest excellence, but none the less a by-product.
Nothing can be more beautiful in its way than a well-grown beech or lime tree; and yet it cannot be held to have been produced for its beauty's sake. The leaves of many trees, shrubs, and plants are scarcely less beautiful than the flowers. But they cannot have been produced by the æsthetic choice of insects. From the depth of a mine there may be brought up a specimen of ruby copper ore, or malachite, or a nest of quartz crystals, or an agate, or a piece of veined serpentine, which shall be at once pronounced a delight to the eye. But for the eye it was not evolved. The grandeur of Alpine scenery, the charm of a winding river, the pleasing undulations of a flowing landscape,—no one can say that these were evolved for the sake of their beauty. The fact of their being beautiful is, therefore, no proof that the blue gentian, or the red admiral, or the robin redbreast were evolved for the sake of, or by means of, the beauty that they possess. Again, one leading feature in the beauty of flowers is their symmetry. The beauty is, so to speak, kaleidoscopic beauty. It is not so much the single veined or marbled petal that is so lovely, as the group of similar petals symmetrically arranged. But this symmetry can hardly be said to have been selected for its æsthetic value; it is rather part of the natural symmetry of the plant. Even with butterflies and birds and beasts the symmetrical element is an important one in their beauty.[IH]
I must not attempt to analyze our sense of beauty or endeavour to trace its origin. It appears to involve a pleasurable stimulation of the sense-organs concerned, together with perceptions of symmetry, of diversity and contrast, and of proportion, with a basis of unity. It is rich in suggestions and associations. It is heightened by sympathy. A beautiful scene is doubly enjoyable if a congenial companion is by our side.
"The whole effect of a beautiful object, so far as we can explain it," says Mr. Sully,[II] "is an harmonious confluence of these delights of sense, intellect, and emotion, in a new combination. Thus a beautiful natural object, as a noble tree, delights us by its gradations of light and colour, the combination of variety with symmetry in its contour or form, the adaptation of part to part, or the whole to its surroundings; and, finally, by its effect on the imagination, its suggestions of heroic persistence, of triumph over the adverse forces of wind and storm. Similarly, a beautiful painting delights the eye by supplying a rich variety of light and shade, of colour, and of outline; gratifies the intellect by exhibiting a certain plan of composition, the setting forth of a scene or incident with just the fulness of detail for agreeable apprehension; and, lastly, touches the many-stringed instrument of emotion by an harmonious impression, the several parts or objects being fitted to strengthen and deepen the dominant emotional effect, whether this be grave or pathetic on the one hand, or light and gay on the other. The effect of beauty, then, appears to depend on a simultaneous presentment in a single object of a well-harmonized mass of pleasurable material or pleasurable stimulus for sense, intellect, and emotion."
This, too, is what I understand by an æsthetic sense of beauty; and if a hen bird has her sexual appetence evoked by the bright display of her mate, the emotional state she experiences is something very different from what we know as a sense of beauty. The adjective "æsthetic" should in any case, I think, be resolutely excluded in any discussion of sexual selection.
Æsthetics, like conceptual thought, accompany the suppression or postponement of action. As we have already seen, the normal and primitive series is (1) sense-stimulus; (2) certain nerve-processes in the brain which are associated with perception and emotion; and (3) certain resulting activities. By the suppression of action the mind comes to occupy itself more and more completely with the central processes. Perception blossoms forth into conceptual thought; emotion blossoms forth into æsthetics.
"'Throughout the whole range of sensations, perceptions, and emotions which we do not class as æsthetic,'[IJ] says Mr. Herbert Spencer, 'the states of consciousness serve simply as aids and stimuli to guidance and action. They are transitory, or, if they persist in consciousness some time, they do not monopolize the attention; that which monopolizes the attention is something ulterior, to the effecting of which they are instrumental. But in the states of mind we class as æsthetic the opposite attitude is maintained towards the sensations, perceptions, and emotions. These are no longer links in the chain of states which prompt and guide conduct. Instead of being allowed to disappear with merely passing recognition, they are kept in consciousness and dwelt upon, their natures being such that their continued presence in consciousness is agreeable.' The action which is the normal consequent on sensation is here postponed or suppressed; and thus we are enabled to make knowledge or beauty an end to be sought for its own sake; and thus, too, we are able to make progress, otherwise impossible, in science and in art. Sensations and perceptions are the roots from which spring the sturdy trunk of action, the expanded leaves of knowledge, and the fair blossoms of art. The leaves and the flowers are the terminal products along certain lines of development; but the function of the leaves is to minister to the growth of the wood, and the function of the flowers is to minister to the continuance and well-being of the race. So, too, in human affairs. Knowledge and art are justified by their influence on conduct; truth and beauty must ever guide us towards right living; and æsthetics are true or false according as they lead towards a higher or a lower standard of moral life."[IK]
To sum up, then, concerning this difficult subject, the following are the propositions on which I would lay stress: (1) What we term an æsthetic sense of beauty involves a number of complex perceptual, conceptual, and emotional elements. (2) The fact that a natural object excites in us this pleasurable emotion does not carry with it the implication that the object was evolved for the sake of its beauty. (3) Even if we grant, as we fairly may, that brightly coloured flowers, in association with nectar, have been objects of appetence to insects; and that brilliant plumage, in association with sexual vigour, has been a factor in the preferential mating of birds;—this is a very different thing from saying that, either in the selection of flowers by insects, or in the selection of their mates by birds, a consciously æsthetic motive has been a determining cause. (4) In fine, though animals may be incidentally attracted by beautiful objects, they have no æsthetic sense of beauty. A sense of beauty is an abstract emotion. Æsthetics involve ideals; and to ideals, if what has been urged in these pages be valid, no brute can aspire.