He hath blinded their eyes, and hardened their heart.... — These words are quoted three times in the New Testament. Our Lord, as we have seen, quotes them as explaining His own teaching (Matthew 13:14); St. John quotes them here to explain the rejection of that teaching; St. Paul quotes them in Acts 28:26, to explain the rejection of the Gospel by the Jews at Rome. Yet we are to remember that the prophet and those who quote him are all witnesses that within Israel there were eyes which were not blinded and hearts which were not hardened. Isaiah, and John, and Paul, were all Jews; and our Lord Himself was, in His human nature, of the seed of Abraham. Isaiah’s prophecy is accompanied by the promise of a holy seed (John 12:13); St. John quotes these words, and adds that “even of the rulers many believed” (John 12:42); St. Paul quotes them when “some believed the things which were spoken and some believed not” (John 12:24); our Lord quotes them, and immediately says, “But blessed are your eyes, for they see, and your ears, for they hear.” There is, indeed, a judicial blinding and a judicial hardening — let no man therefore presume; but these come only to eyes that will not to see, and to hearts that will not to hear — let no man therefore despair. The quotation in this place does not follow exactly either the Hebrew or the Greek of the passage in Isaiah. In the Hebrew text, as in the Authorised version, the prophet is commanded to “make the heart of this people fat.”... The Greek text says simply, “The heart of this people was hardened.”... St. John represents the action which God commanded to be done as done by Himself, and speaks of it in the past tense.
And I should heal them. — The pronoun here refers to Christ. St. John in his interpretation of the prophecy has made God (“He”) the author of the judicial blindness and hardness, and represents Christ as the physician. This clause is, however, not to be taken separately, but is governed by “that not” which precedes, The effect of their not turning was that Christ could not heal them.
On the whole verse comp. Note on Matthew 13:14, and Acts 28:26.