In addition to the legal assassination condoned in the Law against Tyranny, a less extreme method was also available for removing powerful but dangerous men from public life. This was a formal, regular vote for exile, known as ostracism.
Each year the Assembly decided whether a vote of ostracism should be held. If a majority of the quorum of 6,000 citizens voted affirmatively, the day was set and at that time a large open area of the Agora was fenced off. In the enclosure were 10 entrances, one for each of the 10 tribes. By these the citizens entered, each with a potsherd (ostrakon) on which he had scratched the name of the man who seemed to him most dangerous to the state. Officials at the entrance collected the sherds and kept the citizens inside the enclosure until all had voted. The sherds were then tabulated; if more than 6,000 votes were cast, the man whose name appeared on the greatest number was sent into exile for 10 years. Such was ostracism, introduced as a safeguard against tyranny, later used as a weapon by rival statesmen, and finally abandoned in the late fifth century when it deteriorated into a political game.
The potsherds, or ostraka, after being counted, were treated like so much waste paper. They were shoveled up and carried out to fill potholes in the roads leading out from the Agora. The big deposits of ostraka, found on the road from the southwest corner of the Agora, belong to the early years of the fifth century. Stray sherds from the whole area represent later votes of ostracism and provide the names of most of Athens’ prominent statesmen (21, 22).
Themistokles son of Neokles of Phrearrioi, who was soon to become the hero of the Persian War and later to be exiled for pro-Persian sympathies, was a strong candidate for ostracism in 483/2 B.C. It was his chief opponent, Aristeides son of Lysimachos of Alopeke (nicknamed “the just”), who received the greatest number of votes that year and so was ostracized. Kimon son of Miltiades of Lakiadai was voted into exile in the late 460s probably because of his opposition to the radical democrats whom the young Perikles had recently joined. Perikles himself, about whom Thucydides says “by report it was a democracy, in fact a rule of the first citizen,” was never ostracized, but there were votes against him nonetheless. For some citizens, casting a vote was not enough. A few ostraka preserve some rather more violent sentiments. One of the votes against Themistokles adds “Out with him!” Another ostrakon, with the name of Kallixenos, who is not known to us from literary sources, designates him as a “traitor” (22).