The consideration of vision has led us into a region in which, more definitely and precisely than is the case with any other sense, we can observe and even hope to measure the operation of sexual selection in man. In the conception of feminine beauty we possess an instrument of universal extension by which it seems possible to measure the nature and extent of such selection as exercised by men on women. This conception, with which we set out, is, however, by no means so precise, so easily available for the attainment of sound conclusions, as at first it may seem to be. It is true that beauty is not, as some have supposed, a mere matter of caprice. It rests in part on (1) an objective basis of æsthetic character which holds all its variations together and leads to a remarkable approximation among the ideals of feminine beauty cherished by the most intelligent men of all races. But beyond this general objective basis we find that (2) the specific characters of the race or nation tend to cause divergence in the ideals of beauty, since beauty is often held to consist in the extreme development of these racial or national anthropological features; and it would, indeed, appear that the full development of racial characters indicates at the same time the full development of health and vigor. We have further to consider that (3) in most countries an important and usually essential element of beauty lies in the emphasis of the secondary and tertiary sexual characters: the special characters of the hair in woman, her breasts, her hips, and innumerable other qualities of minor saliency, but all apt to be of significance from the point of view of sexual selection. In addition we have (4) the factor of individual taste, constituted by the special organization and the peculiar experiences of the individual and inevitably affecting his ideal of beauty. Often this individual factor is merged into collective shapes, and in this way are constituted passing fashions in the matter of beauty, certain influences which normally affect only the individual having become potent enough to affect many individuals. Finally, in states of high civilization and in individuals of that restless and nervous temperament which is common in civilization, we have (5) a tendency to the appearance of an exotic element in the ideal of beauty, and in place of admiring that kind of beauty which most closely approximates to the type of their own race men begin to be agreeably affected by types which more or less deviate from that with which they are most familiar.