Also on view are ostraca, pottery fragments on which Athenians inscribed the names of persons they felt too powerful for the good of the city and deserving of ostracism, or 10 years’ exile, a procedure formalized by Cleisthenes.
1993, John Fleischman, “In Classical Athens, a market trading in the currency of ideas”, in The Classical Outlook, volume 71, number 1, page 11