What was the Boule?:
The boule was an advisory citizen body of the Athenian democracy. Members had to be over 30 and citizens could serve on it twice, which was more than other elected offices. There were either 400 or 500 members of the boule, who were selected by lot in equal number by each of the ten tribes. In Aristotle's Constitution of Athens, he attributes to Draco a boule of 401 members, but Solon is generally taken as the one who started the boule, with 400.
The boule had its own meeting house, the bouleterion, in the Agora.
Origins of the Boule:
The boule changed its focus over time, so that in the 6th century B.C., the boule was not engaged in civil and criminal legislation, while it was so engaged by the 5th. It is speculated that the boule may have started as an advisory body for the navy or as a judicial body.
The Boule and the Prytanies:
The year was divided into 10 prytanies. During each, all (50) of the councilors from the one tribe (chosen by lot from the ten tribes) served as presidents (or prytaneis). The prytanies were either 36 or 35 days long. Since the tribes were chosen at random, manipulation by the tribes was supposed to be reduced.
The tholos was the dining hall in the Agora for the prytaneis.
Leader of the Boule:
Of the 50 presidents, one was selected as chairman each day. (Sometimes he is referred to as the president of the prytaneis) He held the keys to the treasury, the archives, and the state seal.
Scrutiny of Candidates:
One job of the boule was to determine whether candidates were fit for office. The dokimasia 'scrutiny' included questions that may have been about the candidate's family, shrines for the gods, tombs, treatment of parents, and tax and military status. The members of the boule themselves were exempt for the year from military service.
Pay of the Boule:
In the 4th century, the councilors of the boule received 5 obols when they attended council meetings. The presidents received an extra obol for meals.
The Job of the Boule:
The main task of the boule was to manage the agenda of the assembly, elect certain officials, and question candidates to determine whether they were fit for office. They may have had some power to imprison Athenians before trial. The boule was involved in public finances. They may also have been responsible for inspecting the cavalry and horses. They also met foreign officials.
Sources on the Boule:
Plutarch and Aristotle (Ath. Pol. 'Constitution of Athens') were among the ancient sources.
Christopher Blackwell has written a paper for the STOA project, available for download as PDF called: www.stoa.org/projects/demos/home?greekEncoding=UnicodeC "The Council of 500: its history."