CLEI'STHENES, an Athenian, one of the family of the Aleinieo nidm, was grandson of Cleiethenes, the tyrant of Sicyon. After the expulsion of the Pisistratidie (rte. 510) lie changed his line of politics, and headed the demoeratical party : the opposite faction was con ducted by Isageras. Cleisthenes soon obtained the favour of the people, and the sanction of an oracle from Delphi enabled hies to effect changes in the constitution of Attica which were productive of very important results. The four tribes into which Attica had anciently been distributed gave place to a division altogether new. He made ten tribes, called severally from the name of some hero : each tribe contained a given number of demi (Siam), or townships, which were under the direction each of a denser& (township. governor). Every citizen was obliged to have his name enrolled in the register of some township. Many other changes were also effected.
The senate was increased from 400 to 500; 50 were sent by each tribe. The process of ostracism is said to have been first formally established by Cleisthenes. The Spartan king Cleomenes, acting on the suggestions of Iaageras, insisted on the expulsion of Cleisthenes and the accursed persons. (Herod., v. 70.) Cleisthenes left Athens (Herod., v. 72), but waited a favourable opportunity for prosecuting hie schemes. Seven hundred families were banished at the same time. (Herod., v. 72.) When Cleomenes and Iaagoras were besieged in the citadel which they had occupied, and were forced to capitulate, they left Athena with the Spartan troops, and Cleistheues, with the seven hundred families, returned in triumph. (Thirlwall, Greece, voL pp. 73.80; Niebuhr, Rome, vol. ii. p. 305, &c., Eng. transL)