Nevertheless there arises the intrusive thought, out of bounds for a historian: this was the moment of the great wrong direction taken by the papacy, one which was to outlast the Middle Ages and survive the into our own day. From the time of Gregory can be dated the deliberate clericalisation of the church which was catholic, chaste and free. There was a deep connection between power and a celibacy which helped to distinguish the clergy as a separate and superior caste, distanced in the most profound psychological sense from the family concerns of the laity beneath them. At the time of the reform the church became stamped with certain characteristics which have remained those of the Roman Catholic church: it became papal centred, legalistic, coercive and clerical.’

p. 97, A History of the Medieval Political Thought 300-1450, Joseph Canning, 1996.