Of Pope Gregory VII, in a letter (c. 1070) to Pope Alexander II and Cardinal Archdeacon Hildebrand, Ep. 1. I. ep. 16. T. I. f. 16. - Peter Damian

But if I have erred in anything, I gladly come before the teaching authority of Peter.

But you, my lord and venerable pope, you who take the place of Christ, and the successor to the supreme shepherd in apostolic dignity, do not through sloth allow this pestilence to grow, do not by conniving and dissimulation loosen the reins on this raging impurity. This disease is spreading like a cancer, and its poisonous breed will reach out endlessly unless its evil growth is cut off by the scythe of the gospel.

But now, coming to your shameless assertion that ministers of the altar should be allowed to marry, I consider it superfluous to unsheathe the sword of my own words against you, since we see the armed forces of the whole Church and the massed array of all the holy Fathers ready to resist you. And where so great a host of heavenly troops opposes you, one can only wonder that your novel and rash attempt at doctrine does not submit when confronted by such authority.