Only in appearance does man escape this obligation of Nature. He escapes as an individual, and he submits as a species. The abuse of thought, religious prejudices, vices sterilize a part of humanity; but this fraction is of merely sociological interest; be he chaste or voluptuary, miserly or prodigal of his flesh, man is in his whole condition subject to the sexual tyranny. All men do not reproduce their species, neither do all animals; the feeble and the late-comers among insects die in their robe of innocence, and many nests laboriously filled by courageous mothers are devastated by pirates or by the inclemency of the sky. Let the ascetic not come boasting that he has freed his blood from the pressure of desire; the very importance which he ascribes to his victory but affirms the same power of the life-will. A young girl, before the slightest love affair, will, if she is healthy, confess naively that she "wants to marry to have children." This so simple formula is the legend of Nature. What an animal seeks is not its own life but reproduction. Doubtless many animals seem, during a relatively long existence, to have but brief sexual periods, but one must make allowance for the period of gestation. In principle the sole occupation of any creature is to renew, by the sex act, the form wherewith it is clothed. To this end it eats, to this end builds. This act is so clearly the aim, unique and definite that it constitutes the entire life of a very great number of animals, which are, notwithstanding, extremely complex.
The ephemera is born in the evening, and copulates, the female lays eggs during the night, both are dead in the morning, without even having looked at the sun. These little animals are so little destined for anything else save love that they have not even mouths. They eat not, neither do they drink. One sees them hovering in clouds above the water, among the reeds. The males, although more numerous than the females, perform a multiple duty, and fall exhausted. The purity of such a life is to be admired in many butterflies: the silk-moths, heavy and clumsy, shake their wings for an instant at birth, couple and die. The Great Peacock or Oak Bombyx, much larger than they, eats no more than they do: yet we see him traverse leagues of country in his quest of the female. He has only a rudimentary proboscis and a fake digestive apparatus. Thus his two or three days' existence passes without one egoistic act. The struggle for life, much vaunted, is here the struggle to give life, the struggle for death, for if they can live three days in search of the female they die as soon as the fecundation is accomplished.