The Italian religious reformer Arnold of Brescia (ca. 1100-1155) preached a doctrine of absolute poverty and called for the Church to abandon economic and political power.

Arnold was born at Brescia, and little is known of his youth. He became an Augustinian canon regular and later prior of the monastery in Brescia. He first established himself as a severe critic of the Church in the rebellion against Bishop Manfred, the political ruler of Brescia. On this occasion Arnold outspokenly attacked all forms of ecclesiastical worldliness and corruption. Denounced as a schismatic by the bishop to Pope Innocent II, Arnold soon after heard his proposals for reform condemned by the Second Lateran Council (1139), which banished him from Italy.

Arnold went to France, where he became involved in the conflict between Bernard of Clairvaux and Peter Abelard, taking the side of the latter and possibly becoming his student. In 1140 the...