30 Now if any one should say, “Was it not then possible for God [to bring it to pass] that Moses should look upon that glory and not be injured; and that Paul likewise should look upon the light and take no hurt?” Let him that says this understand that though it is possible for the power and overruling force of God, that the eyes should change their nature; yet it is inconsistent with the wisdom and nature of God that the order of nature should be confused. For, lo!
It is also easy for the arm of the artificer to destroy [his fabrics]; but it is inconsistent with the good sense of the artificer to ruin goodly ornaments. And if any one wishes to say, concerning something which to himself seems meet—“It were meet for God to do this;” let him know that it is meet for himself not to speak thus concerning God. For the chief of all things meet is this: that a man should not teach God what is meet. For it becomes not man to become God's instructor.
For this is a great wickedness, that we should become teachers to Him, of Whom these created mouths of ours are unable to tell, in the formation of His handiwork. For it is an unpardonable iniquity, that the mouth in its boldness should teach what is proper to that God by Whose grace it learned to speak at all. If any one then shall say, “It had been meet for God to do this,” I also, because I have a mouth and a tongue, may say, “It had been meet for God not to give to man freedom by which he thus reproaches Him Who is not to be reproached.”
But I do not dare to say that it was not meet for Him to give it; lest I also make myself an instructor of Him Who is not to be instructed. For because He is just, He would have been reproached by Himself, had He not given freedom to men, as though through grudging He had withheld from lowly man the gift that makes great. Therefore He gave it betimes by His grace, that He might not be justly reproached by Himself; even though through freedom, His own gift, lo! blasphemers wickedly reproach Him.
Source: On Our Lord (New Advent)