Hebrew ethical monotheism was one of the sources of Western Civilization. The other was Greek rational thought that found one of its highest expressions in democratic politics. Greek civilization grew from two earlier civilizations: the Minoans of Crete, and the warlike Mycenaeans of Greece who absorbed Minoan influences and eventually invaded Crete. With the fall of Mycenaean civilization, Greece entered a dark age of tribal migrations from which Hellenic civilization emerged. Urban life and commerce revived, and populations grew such that people left the growing city-states to found colonies. During this period Homer composed the Iliad and the Odyssey, creating characters whose complex thoughts, feelings, and actions deeply influenced later Greek values and thought. These epics also gave shape to dark-age religious beliefs, forming the basis of Olympian religion. As an alternative to Olympianism, the Dionysian, Eleusinian, and Orphic cults offered worshippers ascetic and/or ecstatic experiences. In practice Greek religion was more social than spiritual, and ultimately came to be challenged by secular rational values.

Breaking with the Near Eastern theocratic tradition, Greece developed the self-governing polis as its basic political unit. Initially a tribal and religious institution, the polis evolved into a secular community founded on the belief that laws derive from the rational human mind. The polis reached its greatest development in Athens, but Sparta represented an alternative. Living in fear of helot rebellion, the Spartans developed a militarized polis in which all male citizens served as soldiers. Although Sparta became an important power, its culture grew narrowly provincial. By contrast, Athens developed a more cosmopolitan culture based on a broader conception of free citizenship. Like most city-states, Athens evolved from a monarchy to an oligarchy. Class tensions threatened the oligarchy until Solon weakened aristocratic power and allowed all classes to participate in government. Pisistratus opened cultural life to commoners, and Cleisthenes led Athens to true democracy.

After the Persian Wars, a victorious Athens began a campaign of imperialism. Assuming leadership of the Delian League, Athens used its power to dominate its allies for its own economic gain. During this period Athens also became a direct democracy based on the idea of isonomy. In practice aristocrats continued to dominate politics, and Athenian democracy was limited in that it supported itself through slavery, denied rights to women, and subordinated individual rights to the good of the community. Even so, Athenian democracy did establish the crucial Western principle of the legal state. It also encouraged rational political thought and promoted now-familiar values such as respect for the individual. These ideas and values were embodied by Pericles who led Athens through its golden age with wisdom and selfless civic-mindedness.

Spartan alarm over Athenian imperialism sparked the Peloponnesian war. Although Sparta ultimately defeated Athens, the war weakened all of the Greek city-states, undermining their democracies. During the fourth century constant warfare and civil strife distracted the city-states from the growing threat of Macedonia, which eventually conquered Greece. This conquest exposed the fundamental flaws of Greek politics: the inability to build any system larger than the polis, the inability to sustain the ideal of free citizenship, and the limits of reason as a principle of government and law.