the use of it. It often cost the male a serious amount of trouble—though he never failed to find it worth while—to explain to her the point where he may be allowed to come in, and to persuade her that he can contribute to her enjoyment. So it generally is throughout Nature, before we reach Man, and, though it is not invariably obvious, we often find it even among the unlikeliest animals. As is well known, it is most pronounced among the birds, who have in some species carried the erotic art,—and the faithful devotion which properly accompanied the erotic art as being an essential part of it,—to the highest point. We have here the great natural fact of courtship. Throughout Nature, wherever we meet with animals of a high type, often indeed when they are of a lowly type—provided they have not been rendered unnatural by domestication—every act of sexual union is preceded by a process of courtship. There is a sound physiological reason for this courtship, for in the act of wooing and being wooed the psychic excitement gradually generated in the brains of the two partners acts as a stimulant to arouse into full activity the mechanism which ensures sexual union and aids ultimate impregnation. Such courtship is thus a fundamental natural fact.
It is as a natural fact that we still find it in full development among a large number of peo-
