Still more recently Professor Giard[12] has unearthed from the works of Rousseau the following statement by him regarding species: "Est-ce qu'à proprement parler il n'existerait point d'espèces dans la nature, mais seulement des individus?"[13] In his _Discours sur l'Inégalité parmi les Hommes_ is the following passage, which shows, as Giard says, that Rousseau perfectly understood the influence of the _milieu_ and of wants on the organism; and this brilliant writer seems to have been the first to suggest natural selection, though only in the case of man, when he says that the weaker in Sparta were eliminated in order that the superior and stronger of the race might survive and be maintained. "Accustomed from infancy to the severity of the weather and the rigors of the seasons, trained to undergo fatigue, and obliged to defend naked and without arms their life and their prey against ferocious beasts, or to escape them by flight, the men acquired an almost invariably robust temperament; the infants, bringing into the world the strong constitution of their fathers, and strengthening themselves by the same kind of exercise as produced it, have thus acquired all the vigor of which the human species is capable. Nature uses them precisely as did the law of Sparta the children of her citizens. She rendered strong and robust those with a good constitution, and destroyed all the others. Our societies differ in this respect, where the state, in rendering the children burdensome to the father, indirectly kills them before birth."[14] Soon Lamarck abandoned not only a military career, but also music, medicine, and the bank, and devoted himself exclusively to science. He was now twenty-four years old, and, becoming a student of botany under Bernard de Jussieu, for ten years gave unremitting attention to this science, and especially to a study of the French flora. Cuvier states that the _Flore Française_ appeared after "six months of unremitting labor." However this may be, the results of over nine preceding years of study, gathered together, written, and printed within the brief period of half a year, was no hasty _tour de force_, but a well-matured, solid work which for many years remained a standard one. It brought him immediate fame. It appeared at a fortunate epoch. The example of Rousseau and the general enthusiasm he inspired had made the study of flowers very popular--"_une science à la mode_," as Cuvier says--even among many ladies and in the world of fashion, so that the new work of Lamarck, though published in three octavo volumes, had a rapid success.