http://agathe.gr/democracy/practice_of_ostracism.html
Ostracism Soon after their victory over the Persians at the battle of Marathon in 490 B.C., the Athenians began the practice of ostracism, a form of election designed to curb the power of any rising tyrant ... Aristotle reports the ostracism ... son of Arriphron. Aristotle ... dim.: 0.10 m. Athens, Agora