There are two parts in the sexual act; that of the specie, and that of the individual; but that of the specie is only given it by means of the individual. In relation to the male in rut, it is a question of a very simple natural need. He must empty his spermatic canals: lacking females they say the stag rubs his prong on trees to provoke ejaculation. Bitches in heat rub their vulva on the ground. Such are the rudiments of onanism, suddenly carried by primates to such a high degree of perfection. One has seen male cantharides, themselves ridden, riding other males; the argule, a small crustacean parasite of fresh-water fish, is so ardent that he often addresses himself to other males, or to gravid or even dead females. From the microscopic beasts to man, aberration is everywhere; but one should, rather, call it, at least among animals, impatience. Animals are by no means mere machines, they, as well as men, are capable of imaginations, they dream, they have illusions, they are subject to desires whose source is in the interior movement of their organism. The sight or odour of a female over-excites the male; but far from any female, the logic of the vital movement suffices perfectly to put them in a state of rut; it is absolutely the same with females. If the state of rut, and if the sensibilization of the genital parts is established far from necessary sex, we have here a natural cause of aberration, for it is this special sensibility which must be used: the first simulacrum, or even the first propitious obstacle will be the adversary against which the exasperated animal exercises the energy by which he is tormented. One may apply the general principles of this psychology to man, but on condition that we do not forget that man's genital sensibility is apt to be awakened at any moment, and that for him the causes of aberration are multiplied ad infinitum. There would be extremely few aberrated men and women if moral customs permitted a quite simple satisfaction of sexual needs, if it were possible for the two sexes to meet always at the opportune moment. There would remain aberrations of anatomical order; they would be less frequent and less tyrannic, if our customs, instead of contriving ways to make sexual relations very difficult, should favour them. But this easiness is only possible, in promiscuity, which is possibly a worse ill than aberration. Thus all questions are insoluble, and one can only improve nature by disorganizing her. Human order is often a disorder worse than spontaneous disorder, because it is a forced and premature finality, an inopportune turning of the vital river out of its course.