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 ... (Life of Aristeides 73-4) Ostrakon of Perikles, candidate for ostracism in the mid-5th century B.C. ... Ostrakon of Aristeides, ostracized in 482 B.C. ... (Aristeides 7, translated by Ian Scott-Kilvert) Ostrakon of Kimon, ostracized in 461 B.C.