=Abdera and Athens.= The materialism of Democritus was the natural consummation of the thought of the Cosmological Period. The influence of the Sophistic psychology only enriched it, widened it, and brought its materialism into a systematic formulation. The Democritan system from the isolated centre of Abdera points only to the past. Upon the death of Democritus the school quickly disappeared. Its materialistic doctrine reappeared from time to time in one form and another,――in the Skeptics, the Epicureans, and the Stoics. It was reintroduced as a system into Europe during the Renaissance. So far as Greece was concerned, the school of Abdera was an early ripening and an early dying branch. The school of Athenian immaterialism, the principal tendency of Greek thought, arose from the centre of Attic civilization and pointed to the future. It drew its materials from practically the same sources as the philosophy of Abdera, but the materials were polarized about the ethical teaching of Socrates. The life of Plato coincides with the unhappy history of Athens after the death of Pericles (429 B. C.). The Peloponnesian War began in 431 B. C., two years before the death of Pericles and four years before the birth of Plato; and it did not end until 403 B. C. The event most disastrous to the Athenians during this war was the Sicilian expedition in 413 B. C. Athens was captured by the Spartans in 403 B. C., and the great walls of the city were destroyed. The remainder of Plato’s life was contemporaneous with the devastating wars among the Greek cities, for there was no city strong enough to hold the balance of power after it left the hands of the Athenians. In 359 B. C. Macedon began to loom up as a power in the north. The life of Plato, the formulator of Athenian immaterialism, may be easily remembered as covering that period between the rise of Sparta and the rise of Macedon.