Hippias was expelled in B.C. 510, four years after the assassination of Hipparchus. These four years had been a time of suffering and oppression for the Athenians, and had effaced from their minds all recollection of the former mild rule of Pisistratus and his sons. Hence the expulsion of the family was hailed with delight. The memory of Harmodius and Aristogiton was cherished with the fondest reverence; and the Athenians of a later age, overlooking the four years which had elapsed from their death to the overthrow of the despotism, represented them as the liberators of their country and the first martyrs for its liberty. Their statues were erected in the market-place soon after the expulsion of Hippias; their descendants enjoyed immunity from all taxes and public burdens; and their deed of vengeance formed the favourite subject of drinking songs. The Lacedaemonians quitted Athens soon after Hippias had sailed away, leaving the Athenians to settle their own affairs. Clisthenes, to whom Athens was mainly indebted for its liberation from the despotism, aspired to be the political leader of the state but he was opposed by Isagoras, the leader of the party of the nobles. By the Solonian constitution, the whole political power was vested in the hands of the nobles; and Clisthenes soon found that it was hopeless to contend against his rival under the existing order of things. For this reason he resolved to introduce an important change in the constitution, and to give to the people an equal share in the government. The reforms of Clisthenes gave birth to the Athenian democracy, which can hardly be said to have existed before this time. His first and most important measure was a redistribution of the whole population of Attica into ten new tribes. He abolished the four ancient Ionic tribes, and enrolled in the ten new tribes all the free inhabitants of Attica, including both resident aliens and even emancipated slaves. He divided the tribes into a certain number of cantons or townships, called DEMI, which at a later time were 174 in number. Every Athenian citizen was obliged to be enrolled in a demus, each of which, like a parish in England, administered its own affairs. It had its public meetings it levied rates, and was under the superintendence of an officer called DEMARCHUS.