[187] Fromentin, in his largely autobiographic novel _Dominique_, makes Olivier say: "Julie is my cousin, which is perhaps a reason why she should please me less than anyone else. I have always known her. We have, as it were, slept in the same cradle. There may be people who would be attracted by this almost fraternal relationship. To me the very idea of marrying someone whom I knew as a baby is as absurd as that of coupling two dolls."
[188] It may well be, as Crawley argues (_The Mystic Rose_, Chapter XVII), that sexual taboo plays some part among primitive people in preventing incestuous union, as, undoubtedly, training and moral ideas do among civilized peoples.
[189] The remarks of the Marquis de Brisay, an authority on doves, as communicated to Giard (_L'Intermédiare des Biologistes_, November 20, 1897), are of much interest on this point, since they correspond to what we find in the human species: "Two birds from the same nest rarely couple. Birds coming from the same nest behave as though they regarded coupling as prohibited, or, rather, they know each other too well, and seem to be ignorant of their difference in sex, remaining unaffected in their relations by the changes which make them adults." Westermarck (op. cit., p. 334) has some remarks on a somewhat similar tendency sometimes observed in dogs and horses.
[190] See Appendix to vol. lii of these _Studies_, "The Sexual Impulse among Savages."
[191] See, especially, _ante_, pp. 163 et seq.
[192] Kistemaecker, as quoted by Bloch (_Beiträge, etc._, ii. p. 340), alludes in this connection to the dark clothes of men and to the tendency of women to wear lighter garments, to emphasize the white underlinen, to cultivate pallor of the face, to use powder. "I am white and you are brown; ergo, you must love me"; this affirmation, he states, may be found in the depths of every woman's heart.
[193] K. Pearson, _Grammar of Science_, second edition, p. 430.
[194] In _Man and Woman_ (fourth edition, p. 65) I have referred to a curious example of this tendency to opposition, which is of almost worldwide extent. Among some people it is, or has been, the custom for the women to stand during urination, and in these countries it is usually the custom for the man to squat; in most countries the practices of the sexes in this matter are opposed.