AFTER Plataea, Sparta retired into her shell, but Athens formed a league to make the Aegean safe for Greek freedom. In a series of campaigns her brilliant general, Cimon, swept the seas clear of Persian ships, and of piracy too. These successes enabled Athens to convert the league into an empire before it was thirty years old. She used the contributions which the cities paid to keep the seas clear to adorn herself with beautiful temples. Her specious excuse was that so long as she kept the Persians away, the allies had no right to complain. Athens even attempted to establish a land empire, but was checked by Sparta and Boeotia (445 B.C.). Although Athens was so ready to interfere with Greek liberties, she was herself an example of the most complete liberty. In 461 B.C. the old council of Areopagus, the last stronghold of aristocratic privilege, was stripped of its political importance. Henceforth the popular council of five hundred members, who were appointed by lot from all citizens over the age of thirty, prepared all state business for the decision of the general assembly of all the citizens. The laws were administered by citizen-juries. There were six thousand jurymen from whom smaller juries were chosen by lot for the different cases. The courts were kept busy, for the Athenians insisted that all important cases from all cities of the empire should be brought to Athens. Although the number of slaves equalled that of free citizens, yet with this proviso, it is true that nowhere has the rule of all by all in turn been so completely carried out. Practically every office was open to every one, and the system of appointment by lot, together with the prohibition of re-appointment to the same office, made political experience universally familiar. Even the poorest could serve the state, since a small payment, just enough to buy a bare minimum of food, was given to all jurors and officials. The passion for democracy did not go so far as to leave to chance the direction of state policy, for the ten Generals who managed not only military but also financial and foreign affairs were appointed by election. Re-appointment to this office was permitted, and thus continuity of policy was made possible. Usually, one of the Generals was recognised as commander-in-chief, and exercised power analogous to that of a modern Prime Minister.