Prescription against Heretics 5

Further, if he rebukes dissensions and schisms, which are without doubt evils, he immediately adds heresies too. What he joins to evils he certainly declares to be an evil, and indeed a greater one, since he says he believed what he had heard about schisms and dissensions because he knew that there must also be heresies. For he shows that, in view of the graver evil, he readily believed the lighter ones; not, surely, that he believed the evils because heresies were good, but to warn beforehand that one should not be astonished even at temptations of a worse kind, which he said served to make manifest all who are approved, that is, those whom they had not been able to corrupt. In short, if the whole passage is aimed at keeping unity and curbing separations, and heresies tear men away from unity no less than schisms and dissensions, without doubt he places heresies under the same condemnation as schisms and dissensions. And so he does not make those approved who have turned aside into heresies, since he rebukes above all turning aside to such things, teaching that all should speak one thing and think the same, which heresies do not allow.