6 There was that done in the city of the Thessalonians of which no similar record exists, which I was not able to prevent happening; which, indeed, I had before said would be most atrocious when I so often petitioned against it, and that which you yourself show by revoking it too late you consider to be grave, this I could not extenuate when done. When it was first heard of, a synod had met because of the arrival of the Gallican Bishops. There was not one who did not lament it, not one who thought lightly of it; your being in fellowship with Ambrose was no excuse for your deed. Blame for what had been done would have been heaped more and more on me, had no one said that your reconciliation to our God was necessary.
Source: Letters (New Advent)