Nicene and Post-Nicene Fathers, Ser. II, Vol. XI:
The Works of John Cassian.: Chapter VI. He shows from the appearance of Christ vouchsafed to the Apostle when persecuting the Church, the existence of both natures in Him.

Chapter VI.

He shows from the appearance of Christ vouchsafed to the Apostle when persecuting the Church, the existence of both natures in Him.

Wherefore also, when arguing before King Agrippa and others of the world’s judges, he speaks as follows: “When I was going to Damascus with authority and permission of the chief priests, at midday, O king, I saw in the way a light from heaven above the brightness of the sun, shining round about me and all those that were with me. And when we were all fallen down to the ground, I heard a voice saying unto me in the Hebrew tongue, Saul, Saul, why persecutest thou Me? It is hard for thee to kick against the goad. And I said, Who art Thou, Lord? And the Lord said to me: I am Jesus of Nazareth, whom thou persecutest.” 2427 You see how truly the Apostle said that he no longer knew according to the flesh one whom he had seen in such splendour and majesty. For when as he lay prostrate he saw the splendour of that divine light which he was unable to endure, there followed this voice: “Saul, Saul, why persecutest thou Me?” And when he asked who it might be, the Lord answers and clearly points out His Personality: “I am Jesus of Nazareth, whom thou persecutest.” Now then, you heretic, I ask you, I summon you. Do you believe what the Apostle says of himself, or do you not believe it? Or if you think that unimportant, do you believe what the Lord says of Himself or do you not believe it? If you do believe it, there is an end of the matter:  for you cannot help believing what we believe. For we, like the Apostle, even if we have known Christ according to the flesh, yet know Him so no longer. We do not heap insults on Christ. We do not separate the flesh from the Divinity; and all that is in Christ we believe is in God. If then you believe the same that we believe you must acknowledge the same mysteries of the faith. But if you differ from us, if you refuse to believe the Churches, the Apostle, aye and God’s own testimony about Himself, show us in this vision which the Apostle saw, how much is flesh, and how much God. For I cannot here separate one from the other. I see the ineffable light, I see the inexpressible splendour, I see the radiance that human weakness cannot endure, and beyond what mortal eyes can bear, the glory of God shining with inconceivable light. 2428 What room is there here for division and separation? In the voice we hear Jesus, in the majesty we see God. How can we help believing that in one and the same (Personal) substance God and Jesus exist. But I should like to have a few more words with you on this subject. Tell me, I pray you, if there appeared to you in your present persecution of the Catholic faith that same vision which then appeared to the Apostle in his ignorance, if when you were not expecting it and were off your guard, that radiance shone round about you, and the glory of that boundless light smote you in your terror and confusion, and you lay prostrate in darkness of body and soul; which the unlimited and indescribable terror of your heart increased, 2429 —tell me, I intreat you; When the dread of immediate death was pressing on you, and the terror of the glory that threatened you from above, weighed you down, and you p. 566 heard as well in your bewilderment of mind those words which your sin so well deserves: “Saul, Saul, why persecutest thou Me?” and to your inquiry who it was the answer was given from heaven: “I am Jesus of Nazareth, whom thou persecutest,” what would you say? “I do not know, I do not yet fully believe. I want to think over it with myself a little longer, who I think that Thou art, who speakest from heaven, who overwhelmest me with the brightness of Thy Divinity: whose voice I hear and whose splendour I cannot bear. I must consider of this matter, whether I ought to believe Thee or not: whether Thou art Christ or God. If Thou art God alone whether it is in Christ. If Thou art Christ alone, whether it is in God. I want this distinction to be carefully observed, and thoroughly considered what we should believe that Thou art, and what we should judge Thee to be. For I don’t want any of my offices to be wasted. As if I were to regard Thee as a man, and yet pay to Thee some Divine honours.” If then you were lying on the ground, as the Apostle Paul was then lying, and overwhelmed with the brightness of the Divine light, were at your last gasp, perhaps you would say this, and prate with all this silly chattering. But what shall we make of the fact that another course commended itself to the Apostle; and when he had fallen down, trembling and half dead, he did not think that he ought any longer to conceal his belief, or to deliberate; it was enough for him that he was taught by inexpressible arguments to know that He whom he had ignorantly fancied to be a man, was God. He did not conceal his belief, he made no delay. He did not any longer protract his erroneous ideas by deliberating and disbelieving, but as soon as he heard from heaven the name of Jesus his Lord, he replied in a voice, subdued like that of a servant, tremulous like that of one scourged, and full of fervour like that of one converted, “What shall I do, Lord?” And so at once for his ready and earnest faith, it was granted to him that he should never be without His presence whom he had faithfully believed: and that He, to whom he had passed in heart, should Himself pass into his heart: as the Apostle himself says of himself: “Do you seek a proof of Christ that speaketh in me?” 2430

Footnotes

Acts xxvi. 12-15.

Inæstimabili majestatem Dei luce fulgentem (Petschenig): Gazæus edits Inæstimabilem majestatem, Dei luce fulgentem.

Quas tibi immensus et ineffabilis pavor mentis augeret (Petschenig): Gazæus has Quas tibi immensas et ineffabiles angustias pavor mentis augeret?

2 Cor. xiii. 3.