What, then, was it likely that the master of the slave would choose to receive in his stead? It is possible in the way of inference to make a guess as to his wishes in the matter, if, that is, the manifest indications of what we are seeking for should come into our hands. He then, who, as we before stated in the beginning of this treatise, shut his eyes to the good in his envy of man in his happy condition, he who generated in himself the murky cloud of wickedness, he who suffered from the disease of the love of rule, that primary and fundamental cause of propension to the bad and the mother, so to speak, of all the wickedness that follows—what would he accept in exchange for the thing which he held, but something, to be sure, higher and better, in the way of ransom, that thus, by receiving a gain in the exchange, he might foster the more his own special passion of pride?
Now unquestionably in not one of those who had lived in history from the beginning of the world had he been conscious of any such circumstance as he observed to surround Him Who then manifested Himself, i.e. conception without carnal connection, birth without impurity, motherhood with virginity, voices of the unseen testifying from above to a transcendent worth, the healing of natural disease, without the use of means and of an extraordinary character, proceeding from Him by the mere utterance of a word and exercise of His will, the restoration of the dead to life, the absolution of the damned, the fear with which He inspired devils, His power over tempests, His walking through the sea, not by the waters separating on either side, and, as in the case of Moses' miraculous power, making bare its depths for those who passed through, but by the surface of the water presenting solid ground for His feet, and by a firm and hard resistance supporting His steps; then, His disregard for food as long as it pleased Him to abstain, His abundant banquets in the wilderness wherewith many thousands were fully fed (though neither did the heavens pour down manna on them, nor was their need supplied by the earth producing grain for them in its natural way, but that instance of munificence came out of the ineffable store-houses of His Divine power), the bread ready in the hands of those who distributed it, as if they were actually reaping it, and becoming more, the more the eaters were filled; and then, the banquet on the fish; not that the sea supplied their need, but He Who had stocked the sea with its fish. But how is it possible to narrate in succession each one of the Gospel miracles? The Enemy, therefore, beholding in Him such power, saw also in Him an opportunity for an advance, in the exchange, upon the value of what he held. For this reason he chooses Him as a ransom for those who were shut up in the prison of death. But it was out of his power to look on the unclouded aspect of God; he must see in Him some portion of that fleshly nature which through sin he had so long held in bondage. Therefore it was that the Deity was invested with the flesh, in order, that is, to secure that he, by looking upon something congenial and kindred to himself, might have no fears in approaching that supereminent power; and might yet by perceiving that power, showing as it did, yet only gradually, more and more splendour in the miracles, deem what was seen an object of desire rather than of fear. Thus, you see how goodness was conjoined with justice, and how wisdom was not divorced from them. For to have devised that the Divine power should have been containable in the envelopment of a body, to the end that the Dispensation in our behalf might not be thwarted through any fear inspired by the Deity actually appearing, affords a demonstration of all these qualities at once— goodness, wisdom, justice. His choosing to save man is a testimony of his goodness; His making the redemption of the captive a matter of exchange exhibits His justice, while the invention whereby He enabled the Enemy to apprehend that of which he was before incapable, is a manifestation of supreme wisdom.
Source: The Great Catechism (New Advent)