Roman Catholicism, History Of, The rise of heresy

Before the middle of the 12th century heresy on a large scale was unknown in the West. The early dissenters were often radical reformers such as the Italian canon Arnold of Brescia (d. 1155), an outspoken critic of clerical wealth and corruption. Then there appeared in northern Italy and southern France the sect, Eastern and Manichaean in origin, later known as the Cathari (the