Lustrum
among the Romans, was the purification, or absolution from sin, of the entire people. It
took place at the close of each
census (q.v.),
commonly in May of the year following the censors' accession to office. The host of the
people, horse and foot, in their newly constituted classes, was drawn up in full armour on the
Campus Martius under the leadership of the censor to whom this duty fell by lot. The
Suovetaurilia—a pig, ram, and bull—were carried three
times round the whole army, and thereupon sacrificed to Mars, accompanied by a prayer of the
censor in which he besought that the power of the Roman people might be increased and
magnified, or, as it ran later, might be maintained entirely undiminished. The censor then led
the army under his banner to the city gate, where he dismissed them, while he himself, as a
token of the completed
lustrum, drove a nail into the wall of a temple
and deposited the new roll of citizens in the Aerarium. The last
lustrum
took place in A.D. 74, under Vespasian.