Within the Kantian philosophy of morals there is an idea which conducts necessarily to a philosophy of society and the State. Leibniz was the great German source of the philosophy of the enlightenment. Harmony was the dominant thought of this philosophy; the harmony of nature with itself and with intelligence; the harmony of nature with the moral ends of humanity. Although Kant was a true son of the enlightenment, his doctrine of the radically dual nature of the legislation of Reason put an end to its complacent optimism. According to Kant, morality is in no way a work of nature. It is the achievement of the self-conscious reason of man through conquest of nature. The ideal of a final harmony remains, but it is an ideal to be won through a battle with the natural forces of man. His breach with the enlightenment is nowhere as marked as in his denial that man is by nature good. On the contrary, man is by nature evil--that is, his philosophical rendering of the doctrine of original sin. Not that the passions, appetites and senses are of themselves evil, but they tend to usurp the sovereignty of duty as the _motivating_ force of human action. Hence morality is a ceaseless battle to transform all the natural desires of man into willing servants of the law and purpose of reason. Even the kindly and sociable instincts of man, in which so many have sought the basis of both morality and organized society, fall under Kant's condemnation. As natural desires, they aspire to an illegitimate control in man's motives. They are parts of human self-love: the unlawful tendency to make happiness the controlling purpose of action. The natural relations of man to man are those of an unsocial sociableness. On the one hand, men are forced together by natural ties. Only in social relations can individuals develop their capacities. But no sooner do they come together than disintegrating tendencies set in. Union with his fellows give a stimulus to vanity, avarice and gaining power over others--traits which cannot show in themselves in individuals when they are isolated. This mutual antagonism is, however, more of a force in evolving man from savagery to civilization than are the kindly and sociable instincts. "Without these unlovely qualities which set man over against man in strife, individuals would have lived on in perfect harmony, contentment and mutual love, with all their distinctive abilities latent and undeveloped." In short, they would have remained in Rousseau's paradise of a state of nature, and "perhaps Rousseau was right when he preferred the savage state to the state of civilization provided we leave out of account the last stage to which our species is yet destined to rise." But since the condition of civilization is but an intermediary between the natural state and the truly or rational moral condition to which man is to rise, Rousseau was wrong.