In a society principally characterized by a non-money economy, such as was that of Archaic Athens, classes were initially defined on the basis of citizens' contribution to the war fund. The upper class undertook the higher administrative and military offices, of which the most prominent were those of polemarch and trierarch . The members of the immediately next class took part in war with their horse (the maintenance of which was expensive) and for that reason were called hippeis. The zeugites - all those, that is, who were able to raise a yoke of oxen - were the main body of the Athenian military force; the so-called hoplites. The thetes, the lower class, did military service only as rowers.

Solon defined the classes with precision, laying down as the criterion the amount of landed revenue. Grain was measured in bushels (medimnoi) and liquids (wine, oil) were measured in metretai . The bushel and the metretes had different volume but the same value between them. Later on, in fact, the value of each was equivalent to one drachma. The upper class was made up of all those who had an income of over five hundred bushels of grain and they were called pentakosiomedimnoi. They had increased obligations as regards the body politic and took part in the more costly choregiai, called liturgies. As a reward, they had access to the upper offices of the archon and treasurer. Even in the Classical period, when in practice any citizen whatever could be elected archon, the treasurers went on being elected from the 'pentakosiomedimnoi'.

The hippeis class was made up of citizens with an income of between 500 and 300 bushels. The zeugitai were those with an income between 300 and 200 medimnoi; those who had less than this belonged to the thetes. These names were current earlier, but after Solon they acquired a clear economic content. Income reckoning on the basis of landed revenue was not appropriate to the demiourgoi (small craftsmen, traders). For this reason a money equivalent was calculated, and shortly afterwards (probably around 581 B.C.) they were given permission to enter the three higher classes, depending on their income (Pollux, Onomasticon 4.165).