32 For, lo! The power of our ears and eyes is in us and is formed in us in its natural manner; and yet our sight and hearing cannot stand before mighty thunder and lightning; first, because they come with vehemence; and secondly, because their potency suddenly surprises and astounds our feebleness. This is what happened to Paul. For the potency of the light suddenly surprised his feeble eyes and injured them. But the greatness of the voice brought low his strength and entered his ears and opened them.
For they had been closed up by Jewish contentiousness as by wax. For the voice did not plough up the ears, as the light injured the eyeballs. Why? But because it was meet that he should hear, but not that he should see. Therefore the doors of hearing were opened by the voice as by a key: but the doors of sight were shut by the light that should open them. Why then was it meet that he should hear? Clearly because by that voice our Lord was able to reveal Himself as being persecuted by Saul.
For He was not able to show Himself by sight as being persecuted; for there was no way whereby this should be, that the son of David should be seen fleeing and Saul pursuing after Him. For this happened in very deed with that first Saul and with the first David. The one was pursuing; the other was being persecuted; they both of them saw and were seen, each by the other. But here the ear alone could hear of the persecution of the Son of David; the eye could not see that He was being persecuted.
For it was in [the person of] others He was being persecuted, while He was Himself in heaven;— He Who beforetime had been persecuted in His own person while He was upon earth. Therefore the ears [of Saul] were opened and his eyes were closed. And He Who by sight could not represent Himself before Saul as persecuted, represented Himself by word before him as persecuted; when he cried and said— Saul, Saul, why do you persecute Me? Accordingly, his eyes were closed, because they could not see the persecution of Christ; but his ears were opened, because they could hear of His persecution.
So then although the eyes of Moses were bodily eyes, as those of Paul, yet his inward eyes were Christian; for Moses wrote of Me, but the outward eyes of Paul were open, while the inward [eyes] were shut. Then because the inward eyes of Moses shone clear, his outward eyes also were made to shine clearly. But the outward eyes of Paul were closed, that by the closing of those that were outward, there might come to pass the opening of those that were inward. For he who by the outward eyes was not able to see the Lord in His signs, he when those bodily eyes were closed, saw with those within.
And because he had received the proof in his own person, he wrote to those who had their bodily eyes full of light— May He illumine the eyes of your hearts. Therefore the signs manifested to the external eyes of the Jews, profited them not at all; but faith of the heart opened the eyes of the heart of the Gentiles. But because, had Moses come down in his accustomed aspect from the mountain, without that shining of countenance, and said, “I saw there the glory of God,” the faithless fathers would not have believed him; so also, had Paul, without suffering blindness of his eyes, said, “I heard the voice of Christ,” the sons who crucified Christ would not have received it as true.
Therefore He set on Moses as in love, an excelling sign of splendour, that the deceivers might believe that he had seen the Divine glory; but on Saul, as on a persecutor, He set the hateful sign of blindness, that the liars might believe that he had heard the words of Christ; that so you might not again speak against Moses, and that these might not doubt concerning Paul. For God set signs on the bodies of the blind, and sent them to those who were in error, who used to make signs upon the borders of their garments.
But they remembered not the signs on their garments, and in the signs of the body they greatly erred. The fathers who saw the glory of Moses, did not obey Moses; nor did the sons who saw the blindness of Paul believe Paul. But three times in the desert they threatened to stone Moses and his house with stones as dogs. For all congregation bade stone them with stones. And thrice they scourged Paul with rods as a dog on his body. [?] Thrice was I beaten with rods. These are the lions who through their love for their Lord were beaten as dogs and were torn as flocks of sheep, those flocks that used to stone their guardian shepherds, in order that ravening wolves might rule over them.
Source: On Our Lord (New Advent)