Zeno of Cyprus, the founder of the Stoic School, a Greek of Phoenician descent, was born about 342 B.C., and died in 270. He is said to have followed philosophy; because he lost all his property in a ship-wreck--a motive characteristic of the age. He came to Athens, and learned philosophy under Crates the Cynic, Stilpo the Megaric, and Polemo the Academic. About 300 B.C. he founded his school at the Stoa Poecile (many-coloured portico) whence the name Stoic. He died by his own hand. He was followed by Cleanthes, and then by Chrysippus, as leaders of the school. Chrysippus was a man of immense productivity and laborious scholarship. He composed over seven hundred books, but all are lost. Though not the founder, he was the chief pillar of Stoicism. The school attracted many adherents, and flourished for many centuries, not only in Greece, but later in Rome, where the most thoughtful writers, such as Marcus Aurelius, Seneca, and Epictetus, counted themselves among its followers. We know little for certain as to what share particular Stoics, Zeno, Cleanthes, or Chrysippus, had in the formation of the doctrines of the school. But after Chrysippus the main lines of the doctrine were complete. {345} We shall deal, therefore, with Stoicism as a whole, and not with the special teaching of particular Stoics. The system is divided into three parts, Logic, Physics, and Ethics, of which the first two are entirely subservient to the last. Stoicism is essentially a system of ethics which, however, is guided by a logic as theory of method, and rests upon physics as foundation. Logic. We may pass over the formal logic of the Stoics, which is, in all essentials, the logic of Aristotle. To this, however, they added a theory, peculiar to themselves, of the origin of knowledge and the criterion of truth. All knowledge, they said, enters the mind through the senses. The mind is a _tabula rasa_, upon which sense-impressions are inscribed. It may have a certain activity of its own, but this activity is confined exclusively to materials supplied by the physical organs of sense. This theory stands, of course, in sheer opposition to the idealism of Plato, for whom the mind alone was the source of knowledge, the senses being the sources of all illusion and error. The Stoics denied the metaphysical reality of concepts. Concepts are merely ideas in the mind, abstracted from particulars, and have no reality outside consciousness.