Cleisthenes

Cleisthenes (c. 570–508 BCE) was an Athenian statesman from the Alcmaeonid clan who is traditionally credited with laying the foundations of Athenian democracy. Coming to prominence after the fall of the Peisistratid tyranny, he initiated a series of constitutional reforms around 508–507 BCE that reshaped Athenian politics and civic identity.

His most consequential measures reorganized the Attic political landscape. He created 139 demes (local units) and redistributed them into 30 trittyes and 10 new tribes (phylae), mixing urban, coastal, and inland communities to dilute old regional loyalties. This demic and tribal restructuring aimed to foster broader participation and weaken aristocratic factions.

Cleisthenes also established the Council of 500 (Boule), selecting 50 members from each tribe by lot for a one-year term. The Boule prepared legislation and oversight for the Ekklesia (the Assembly), which gained greater authority in governing the polis. He reduced the power of the Areopagus, the aristocratic council, while preserving its role as a judicial and supervisory body.

Ostracism, a mechanism attributed to his reforms, provided the Assembly with a means to exile a citizen deemed a threat to the state for ten years, thereby curbing potential tyrants and consolidations of power.

The Cleisthenic reforms are regarded as foundational to Athenian democracy, shaping citizenship organization, civic participation, and the balance between institutions. While subsequent reforms by other leaders built on these changes, Cleisthenes’ program is seen as a turning point in the development of Athenian political life. Note that a contemporary Cleisthenes of Sicyon is a different historical figure.