Blessed are the heretics

I have always attributed the line "blessed are the heretics" to Stanley Hauerwas, who in his typical fashion goes on to say (paraphrasing from memory) that without the heretics the church would not be instigated into growing ever more deeply into the truths of the faith. Indeed, a quick Google search found this quote, which I'm sure is a regularly repackaged line:

"In truth, we are never quite sure what we believe until someone gets it wrong. That is why those we call heretics are so blessed because without them we would not know what we believe."

There he goes on to discuss the Apollinarian heresy as an instance of the church establishing, through hard-win effort, a more rigorous christological grammar than it previously had.

Re-reading the Confessions the other day, though, I saw that St. Augustine says something similar. In Book VII, while discussing the "books of the Platonists" and their relationship to the faith, he writes first of his friend, then of himself:

"[Alypius's] move towards the Christian faith was slower. But later when he knew that this was the error of the Apollinarian heretics, he was glad to conform to the Catholic faith. For my part I admit it was some time later that I learnt, in relation to the words 'The Word was made flesh,' how Catholic truth is to be distinguished form the false opinion of Photinus."

He continues:

"The rejection of heretics brings into relief what your Church holds and what sound doctrine maintains. 'It was necessary for heresies to occur so that the approved may be made manifest' among the weak." (VII.xix.25)

I'm curious: Who first spoke this way about heretics in the tradition, and after Augustine, did it become a mainstay? My reading in medieval heresiology is vanishingly small. I suppose I'm interested less in the general sentiment (which I'm sure is common) and more in poetic or providential or even positive language about heretics and their heresies as occasions for growth in catholic truth.
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