Explanations are vain in these matters. They divert the curiosity without satisfying the reason. What one sees clearly is a necessity: the act must be accomplished, to this end, all obstacles, whatever they are, will be overcome. Neither distance, nor the difficulty of the voyage, nor the danger of the approach can drive back the instinct. In man, who has sometimes the power to escape the sexual commandments, disobedience may have happy results. Chastity, as a transmuter, may change unused sexual energy into intellectual or social energy; in animals this transmutation of physical values is impossible. The compass needle remains in one immutable position, obedience is unescapable. That is why there is so deep a rumble in nature when the spring orders are posted. Vegetable flowers are not the only ones to open: sexes of flesh also flower. Birds, fish take on new and more vivid colours. There are songs, plays, pilgrimages. Salmon who live quietly at the river-mouths, must gather, depart, climb the streams, pass weirs, scrabble against rocks which form the dams and cataracts, wear themselves out leaping as arrows against all human and natural obstacles. Males and females arrive worn out at the end of their journey, the _frayère_ of fine sand where they are to lay their eggs, and the males heroically to spend the milt distilled from their blood.
Spring is not the only rutting season. Love's calendar covers the year. In winter, wolves and foxes; in spring, the birds and fish; in summer, insects and many mammals; in autumn the deer. Winter is often the season chosen by polar animals; the sable couples in January; the ermine in March; the glutton, at the beginning and end of winter. Domestic animals have often several seasons; for the dog, cat and house-birds, spring and autumn. One finds young otters at any time. Most insects die after mating; but not all hemiptera, nor the queen bee, nor certain coleoptera, nor certain flies. The stag and the stallion empty themselves, but not the ram, nor the bull nor the he-goat. The duration of pregnancy in placentaires seems to have some relation to the size of the animal; mare, eleven to twelve months; ass, twelve months and a half; cow, doe, nine months; sheep, goat, wolf, vixen, five months; sow, four months; bitch, two months; cat, six weeks; rabbit, one month.