The senses, as one knows, are substitutable one for the other, in a certain degree; but in the normal state they seem rather to reinforce each other mutually, and lend each other a certain support. One does not shut the eyes to hear better, save when one has determined the source of the sound. And even then, is it to hear better? Is it not rather to reflect and to hear at the same time, to manage an interior concentration with which the eye, essentially an explorative organ, would interfere? It is in love that this alliance of all the senses is most intimately exercised. In superior animals, as well as in man, each sense, together or in groups, comes to reinforce the genital sense. None remain inactive, eye, ear, scent, touch, even taste come into play. Thus one explains the gleam of plumage, the dance, song, sexual odours. The female eye, in birds, is more sensitive than the male eye; the contrary is true of humanity; but female birds and women are particularly moved by song or words. The two sexes in dogs have, equally, recourse to scent; sight seems to play but an insignificant rôle in their sexual access, since minuscule canine beasts do not fear to address themselves to monsters, which for man would be in proportion more than that of a mammoth. Insects before mating often caress each other with their mysterious antennæ; the male is sometimes given a sounding apparatus: cricket and grasshopper drum to charm their companions. It is not necessary to explain how in humans, especially in the male, all the senses concur in the amour, at least when moral and religious prejudices do not stop their impetus. It should be so, in an animal so sensitive, and of so complex and multiple a sensibility. The abstention of a single sense from the coupling is enough to enfeeble the pleasure very greatly. The coldness of many women may proceed less from a diminution of their genital sense, than from the general mediocrity of their senses. Intelligence, being but the ripe fruit of the general sensibility, its intensity is very often found to be in a certain relation with the sexual sensibility. Absolute coldness might signify stupidity. There are, however, too many exceptions for one to generalize in this matter. It happens indeed that intelligence instead of being the sum total of the sensibility, is, so to speak, the deviation or transmutation. There remains very little sensibility; it is nearly all turned into intelligence.