Reference has already been made to what was done by Solon in the beginning of the sixth century B.C. to establish a constitutional form of government, in which all classes of the population, slaves only excepted, should have some degree of representation. The form of government which Solon introduced has been called a _timocracy_--property, not birth or rank, being the standard of political power. He divided the population into four classes, the highest consisting of citizens who possessed 500 medimni of corn. It was from this last class alone that the nine archons--Ministers of State in a restricted sense--and the _strategoi_ or generals had to be chosen. All other offices were open to the whole population--the lowest class or _Thetes_ alone excepted, whose eligibility was confined to serving as _dicasts_ or jurymen, and who were exempted from the graduated income-tax imposed on the three higher classes. All citizens had a right of membership in the _Ecclesia_ or popular assembly, to which the _Boulé_ or Council of 400, selected by lot, had to submit any proposals of a legislative character. A special benefit was at the same time conferred upon the distressed agriculturists by a measure called _Seisachtheia_, for relieving them more or less from the burdens which their costly mortgages had entailed upon them. Still more democratic measures were introduced, nearly a century later, by Cleisthenes, a member of the Alcmæonid family. He abolished all class distinctions, with the single exception that the office of archon was still confined to the highest of the four classes recognised by Solon. He also divided the community into ten tribes; increased the number of the _Boulé_ to 500, 50 being chosen from each tribe; and gave to the general Assembly, of which all citizens above eighteen years of age were members, a more definite and secure place in the constitution. No one was eligible for public office till he was thirty years of age. From each of the ten tribes 600 _dicasts_ were annually appointed by lot, 5000 of the total number being required for service in the law courts, and the remaining 1000 for revision of the laws. It was also with Cleisthenes that the measure known as _Ostracism_ originated. It gave the assembly power in any political emergency to banish from the country for ten years (later the period was changed to five years) [Illustration: THE ACROPOLIS FROM THE BASE OF THE PHILOPAPPUS HILL