Augustine of Hippo
Catena Aurea · Johannesevangelium 12
But though he had done so many miracles before them, yet they believed not on him: That the saying of Esaias the prophet might be fulfilled, which he spake, Lord, who hath believed our report? and to whom hath the arm of the Lord been revealed? Therefore they could not believe, because that Esaias said again, He hath blinded their eyes, and hardened their heart; that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them. These things said Esaias, when he saw his glory, and spake of him. Nevertheless among the chief rulers also many believed on him; but because of the Pharisees they did not confess him, lest they should be put out of the synagogue: For they loved the praise of men more than the praise of God.
(Tr. liii. 5) But what follows involved a deeper question: Therefore they could not believe, because that Esaias said again, He hath blinded their eyes, and hardened their hearts, that they should not see with their eyes, nor understand with their heart, and be converted, and I should heal them. That they should not believe; but if so, what sin is there in a man doing what he cannot help doing? And what is a graver point still, the cause is assigned to God; since He it is who blinded their eyes, and hardened their heart. This is not said to be the devil’s doing, but God’s. Yet if any ask why they could not believe, I answer, Because they would not. For as it is to the praise of the Divine will that God cannot deny Himself, so is it the fault of the human will that they could not believe.