As I follow no leader save Christ, so I communicate with none but your blessedness, that is, with the Chair of Peter. For this, I know, is the rock on which the Church is built. … This is the ark of Noah, and he who is not found in it shall perish when the flood prevails. … And as for heretics, I have never spared them; on the contrary, I have seen to it in every possible way that the Church's enemies are also my enemies.
Jerome, (405–420), Manual of Patrology and History of Theology.