=The Position of Stoicism in Antiquity.= The Stoic School had a long history, and for five hundred years it was well-nigh the dominating system of thought. Its importance is shown in the attacks on all sides by which it was honored. It was subjected to a continued critical testing by the Peripatetics, Epicureans, Skeptics, and the Academy. It was without doubt the most comprehensive School of the Hellenic-Roman Period, and numbered as its adherents the most brilliant personalities of the time. In its importance to history its only rival was neo-Platonism, which came after it. Stoicism accomplished much toward solving the problem of life, for it is one of the great inner, spiritual movements of humanity. It was a system of philosophy raised upon the ruins of polytheism――a religion for the educated classes, who tried to harmonize the old religion with the new philosophic needs. In the early Christian centuries it led the moral reform by reviving the classic ideals. It became a retreat into the invisible order, a solace amid unrest. Particularly at that time the Stoic felt the emptiness of human life, for his possession of eternity made earthly existence seem as nothing. Yet it was a movement of subjective reflection and individual motive; but as such it could not prove itself adequate when the structure of Roman society broke down. But we must not take the _Roman_ Stoics as the representatives of the sect. The Stoics stood for more than moral reflection. The great achievement came from the first three leaders――_the achievement of giving a scientific basis to morals_. The Stoics made ethics an independent science. Such an elaborate system of morals as that of the Stoics had never before existed. Stoicism was morality with a theoretical foundation, and the foundation was the most imposing part of the edifice. This appeared in Roman jurisprudence, and in later times in Grotius, Descartes, Spinoza, the Calvinists and Puritans, and in Kant and Fichte. The writings of the individual Stoics have become a part of the world’s literature, and the Stoic view of life has maintained itself as a dignified and independent type. =The Three Periods of Stoicism.= The five hundred years of the history of the Stoic School are usually divided into three periods. The first is about 90 years long, in which the doctrine was formulated; the second is 200 years long, when the doctrine was modified; the third was 200 years long, when it became a popular moral philosophy. The first two periods were theoretical, the third was practical. =1. Period of Formulation of the Doctrine= (294 B. C.–206 B. C.), sometimes called the period of Cynical Stoicism. This period contains the three great leaders: Zeno (340–265 B. C.), Cleanthes, leader of the School from 264 to 232 B. C., and Chrysippus (280–206 B. C.). Zeno of Tarsus, Diogenes of Seleucia, and Antipater of Tarsus were other important representatives.