According to Grotius such _jus naturale_—the only branch of legal studies that can be treated is philosophy—is based on the essence of the nature of men. But such nature is the same all over the world just as Nature is. It will be the same for ever in spite of historical oscillations just as Nature will. The presupposition of this nature of man, postulated out of and against every experience, is a negation of history as the process of the gradual development of mankind. Yet unquestionably its introduction in modern politics was the cause of a great progress towards justice, and in Grotius himself it is balanced by his insistence on not taking positive law out of history. The lack of good metaphysical ground brought him to the postulation of an unhistorical reality whilst the recent improvement of historical researches at the hands of Jean Bodin and others induced him not to consider positive laws except in the light of history. To be fair, this instinct of society deeply inset in the nature of man was not of his own invention. It is to be found in Aristotle. It is to be found in St. Thomas. But then the instinct compelling man to live in community is understood in a very different way by the Greek philosopher, by the great Scholastic doctor and by the Dutch statesman. For if it is true that historical facts which are political, artistic, military, receive their definite character from the ideas of the generation that achieved them, it is equally true that the meaning attached to traditional ideas by any one man is to a certain extent modified by the whole life of his generation. So that Aristotle understands by Nature the transcendental power which planned the life of man as a part of its universal scheme; Thomas Aquinas sees in the nature of man that which was determined as characteristic of mankind by the Divine will; whilst Grotius sees in this sense of society something very much like the law of gravitation—not quite, however, since in him we see looming out already the ghost of man anterior to society, of whom nobody ever heard anything and which is, therefore, a pure conjecture. Considering this nature of mankind as his basis, it was inevitable that Grotius should think the best constitution of the state to be one the origin of which made it more likely to meet the requirements of such nature. Once the filiation of law as the product of this nature of man was established, private and public law obviously derived from the _jus naturale_, and the state must originate from an agreement of its components.