Ser'vius divided all the Romans into classes and centuries according to their wealth and the amount of taxes paid to the state.

The number of centuries in the first class nearly equalled that of all the others; a great advantage to the plebeians; for the lower classes being chiefly clients of the patricians, were always inclined to vote according to the prejudices or interests of their patrons.
6.

The classification by centuries was also used for military purposes; the heavy armed infantry being selected from the richer classes; the light troops, whose arms and armour could be obtained at less expense, were levied among the lower centuries.
7.

In order to ascertain the increase or decay of his subjects, and their fortunes, he instituted another regulation, which he called a _lustrum_.

By this, all the citizens were to assemble in the Cam'pus Mar'tius,[2] in complete armour, and in their respective classes, once in five years, and there to give an exact account of their families and fortune.
8.