The death of Alexander the Great (356–323 B.C.E.) marked the end of the classical period in Greek philosophy. The Greek cities were unable to unify after great losses in the Peloponnesian War (431–404 B.C.E.). The next 800 years marked a period of great instability, as the political and cultural center of Western civilization shifted to Europe. As Rome came to dominate Greece, the uncontested brilliance of the Greeks faded into the past. Toward the end of this historical period, Christian thought and practice began to define almost every aspect of civilized life.

Some Pre-Socratic thought—particularly the ideas and practices of Pythagoras—lived on after the decline of Greece; Plato’s work endured in new forms that were compatible with early Christianity. The Hellenistic or Greek-based forms of the new philosophies of skepticism, stoicism, Epicurianism, and cynicism spread throughout the Mediterranean world. There was little awareness of Aristotle’s work at the time, although empiricism was easily accepted.