This statement must of course not be taken to mean that the Stoics first developed their ethical principles independently of their theory of the universe, and afterwards brought the two into connection with each other. On the contrary, it was by the peculiar connection of theory and practice that Stoicism itself first came into existence. The leading thought of Zeno consists in the attempt to vindicate the supremacy of virtue by a scientific knowledge of the laws of the world; and he becomes the founder of a new School only by bringing to Cynicism those scientific ideas and aims which he had learned himself in the School of Polemo, Stilpo, and Diodorus, or otherwise gathered from a study of ancient philosophy. These elements are not therefore accidentally brought together in Stoicism, but they are co-extensive, and dependent one upon the other. As in the natural science and theory of knowledge of the Stoics, the experimental basis on which their system was built may be easily seen, so the peculiar development of their ethics supposes all those positions respecting the universe and the powers therein at work, which form the most important part of their natural science. Only by a scientific treatment of this kind was Stoicism at all able to improve upon the imperfection of the Cynic ethics, so far at least as it really did so, and to accommodate itself to the wants of human nature, so far as to be able to exercise an influence at large. Upon this union of ethics and metaphysics that religious attitude of the Stoic system reposes, to which it owes in a great measure its historical importance. Thereby it occupies so influential a position in an age in which intellectual power was indeed declining, but in which the interest for science was keen. But that Stoic physics and metaphysics should have adopted this line, and no other; that Zeno and his followers, who draw on former systems for their own on the most extensive scale, should have borrowed from these systems these and no other positions, and expanded them in this and no other direction; these results are, doubtless, ultimately due to their moral attitude. All that bore on the subject of ethics, and supported it, they appropriated; all that was opposed thereto they rejected. The Stoic system as such owes its rise to a union of ethical and speculative elements, in which both were more definitely determined by one another; still the ethical platform is the one on which its formation commences, and which primarily determined its course and results. [B. Relation of Stoicism to previous systems.] [(1) Its relation to Socrates and the Cynics.]