While, therefore, this analysis seems to include all the phenomena and to be worthy of very careful study as a serious and elaborate attempt to present an adequate psychological definition of the sexual impulse, it scarcely seems to me that we can accept it in precisely the form in which Moll presents it. I believe, however, that by analyzing the process a little more minutely we shall find that these two constituents of the sexual impulse are really much more intimately associated than at the first glance appears, and that we need by no means go back to the time when the sexual method of reproduction arose to explain the significance of the phenomena which Moll includes under the term contrectation. To discover the true significance of the phenomena in men it is necessary to observe carefully the phenomena of love-making not only among men, but among animals, in which the impulse of contrectation plays a very large part, and involves an enormous expenditure of energy. Darwin was the first to present a comprehensive view of, at all events a certain group of, the phenomena of contrectation in animals; on his interpretation of those phenomena he founded his famous theory of sexual selection. We are not primarily concerned with that theory; but the facts on which Darwin based his theory lie at the very roots of our subject, and we are bound to consider their psychological significance. In the first place, since these phenomena are specially associated with Darwin's name, it may not be out of place to ask what Darwin himself considered to be their psychological significance. It is a somewhat important question, even for those who are mainly concerned with the validity of the theory which Darwin established on those facts, but so far as I know it has not hitherto been asked. I find that a careful perusal of the _Descent of Man_ reveals the presence in Darwin's mind of two quite distinct theories, neither of them fully developed, as to the psychological meaning of the facts he was collecting. The two following groups of extracts will serve to show this very conclusively: "The lower animals have a sense of beauty," he declares, "powers of discrimination and taste on the part of the female" (p. 211[21]); "the females habitually or occasionally prefer the more beautiful males," "there is little improbability in the females of insects appreciating beauty in form or color" (p. 329); he speaks of birds as the most "esthetic" of all animals excepting man, and adds that they have "nearly the same taste for the beautiful as we have" (p. 359); he remarks that a change of any kind in the structure or color of the male bird "appears to have been admired by the female" (p. 385). He speaks of the female Argus pheasant as possessing "this almost human degree of taste." Birds, again, "seem to have some taste for the beautiful both in color and sound," and "we ought not to feel too sure that the female does not attend to each detail of beauty" (p. 421).