proper apprehension as by subjective ideas exciting desire, which arise from the influence of the ganglion system upon the brain, and accordingly by a kind of illusion; and this will be the physiological process in the case of all instinct. For the sake of illustration I will mention as another example of instinct in the human species, although a weak one, the capricious appetite of women who are pregnant. It seems to arise from the fact that the nourishment of the embryo sometimes requires a special or definite modification of the blood which flows to it, upon which the food which produces such a modification at once presents itself to the pregnant woman as an object of ardent longing, thus here also an illusion arises. Accordingly woman has one instinct more than man; and the ganglion system is also much more developed in the woman. That man has fewer instincts than the brutes and that even these few can be easily led astray, may be explained from the great preponderance of the brain in his case. The sense of beauty which instinctively guides the selection for the satisfaction of sexual passion is led astray when it degenerates into the tendency to pederasty; analogous to the fact that the blue-bottle (Musca vomitoria), instead of depositing its eggs, according to instinct, in putrefying flesh, lays them in the blossom of the Arum dracunculus, deceived by the cadaverous smell of this plant.
Now that an instinct entirely directed to that which is to be produced lies at the foundation of all sexual love will receive complete confirmation from the fuller analysis of it, which we cannot therefore avoid. First of all we have to remark here that by nature man is inclined to inconstancy in love, woman to constancy. The love of the man sinks perceptibly from the moment it has obtained satisfaction; almost every other woman charms him more than the one he already possesses; he longs for variety. The love of the woman, on the other hand, increases just from that moment. This is a consequence of the aim of
