Quaestiones Evangeliorum de tempore et de sanctis

I respond that it must be said that for God to be incarnate was in one way necessary and in another way not. For this, it must be noted, according to Saint Thomas Aquinas, that something is said to be necessary for an end in two ways. In one way, without which the end cannot be had, just as food is necessary for the preservation of human life. In another way, it is called necessary by which the end is reached better and more conveniently, just as a horse is necessary for a journey. In the first way of necessity, it was not necessary for God to be incarnate for the reparation of human nature. God, indeed, through His omnipotent virtue, could have repaired human nature in many other ways. In the second way of necessity, however, it was necessary for God to be incarnate for the reparation of human nature. Augustine Saint Augustine of Hippo puts forward this conclusion in the thirteenth book of On the Trinity: "Let us show that no other possible way was lacking to God, to whose power all things are equally subject, but that there was no other way more fitting for the healing of our misery." The necessity or fittingness of this incarnation is taken from three things: namely, from the plenitude of divine mercy, from the immutability of His justice, and from the recent order of His wisdom. Because God is supremely good and merciful, it was fitting that this, of which [human nature] is capable, be denied to no creature. Whence, since human nature had fallen and nevertheless remained repairable, it was fitting that He repair it. Because His justice is also immutable, by whose law it is sanctified that sin is never dismissed without satisfaction, it was fitting that there be one in human nature who could make satisfaction. And because a pure man could not do this by himself, as has been said, it was fitting that God, who is supremely wise, should find some most fitting mode of reparation. Whence, it is most fitting that nature be integrated and repaired, so that man could easily attain that which he had lost. If, however, He had repaired man through an angel, the reparation would not be integral, because man would always be a debtor of his salvation to the angel, and thus he could not be equal to him in beatitude, which, however, he would have desired if he had not sinned, just as now men obtain through the grace of reparation that they are as the angels of God in heaven (Matthew xxii). And therefore it was fitting that not an angel, but God Himself, should repair man. Many other fitting reasons are assigned for the Incarnation which we pass over for the sake of brevity and because they are common in sermons. To the arguments on the contrary, it must be said: To the first, it is responded that that argument proceeds according to the mode of necessity without which the end cannot be reached. But it has been said that in that mode of necessity, it is not necessary for God to be incarnate. To the second, it is responded by denying the consequence. The reason is that, although God is supremely merciful, His mercy in no way opposes His justice. For mercy that removes justice ought to be called folly rather than virtue, and consequently, such does not befit God.