Book Four — Salvation, Chapter 55 — Summa Contra Gentiles
[1] Now, then, the points opposed to this doctrine above are disposed of easily.
[2] It is not contrary to the order of things for God to become man, as the first argument proceeded. This is the case because, although the divine nature exceeds the human nature to infinity, man in the order of his nature has God Himself for end and has been born to be united to God by his intellect And this union had as example and testimony of a sort the union of God to man in person; nonetheless, what was proper to each nature was preserved, so that nothing of the excellence of the divine nature was lost, nor was there an exaltation which drew the human nature beyond the bounds of its species.
[3] There is the following to be considered, also. By reason of the perfection and immobility of the divine goodness, God loses no dignity no matter how closely a creature draws near to Him, although this makes the creature grow in dignity. For He communicates His goodness to creatures in such wise that He Himself suffers no loss.
[4] In like fashion, too, one grants that God’s will suffices for doing all things; nevertheless, the divine wisdom requires that provision be made for the various classes of things in harmony with themselves, for He has suitably established the proper causes of various things. Be it granted, accordingly, that God was able by His will alone to effect in the human race every useful good which we are saying came from God’s Incarnation, as the second argument was proposing; nevertheless, it was in harmony with human nature to bring about these useful goods through God made man, just as the arguments giveng make apparent to some extent.
[5] The answer to the third argument is also plain. For, since man is constituted of a spiritual and of a bodily nature, and stands, so to say, on the boundary of each nature, that appears to belong to the whole of creaturehood which is done for the salvation of man. For the lesser bodily creatures seem to yield to man’s use and are in some way subject to him. But the superior spiritual, namely the angelic, creature has the achievement of the ultimate end in common with man (this is plain from the foregoing). Thus, it seems suitable that the universal cause of all things assume that creature into unity of person in which the cause shares more with other creatures.
[6] This fact should be considered, also: To act of itself belongs only to the rational creature, for irrational creatures are more acted upon by a rational force than they are acting of themselves. Hence, they are rather in the order of instrumental causes than bearing themselves as principal agents. But the assumption of a creature by God had to be of the kind which could act of itself as a principal agent. For whatever acts as an instrument acts as moved into action, but a principal agent acts of itself. If, then, something was to be done divinely by an irrational creature, it sufficed, the creature’s condition considered, that it merely be moved by God. But it would not be assumed in person for the person to actq since its natural condition was not susceptible of this, it was only the condition. of the rational nature which was so susceptible. Therefore, for God to assume an irrational creature was not suitable, whereas to assume a rational one, whether human or angelic, was.
[7] And, although one finds in the angelic nature natural properties making it more excellent than the human nature, as the fourth argument was proposing, the human nature was nevertheless assumed with greater fitness. First, indeed, this is because in man sin is subject to expiation; and this is so because his choice is not unchangeably fixed on something, but can be perverted from good to evil, and from evil restored to good. In man’s reason, also, this happens: Since it gathers the truth from sensible things and certain signs, the way lies open to contradictory positions. But an angel, just as he has an unchangeable grasp of truth because he knows by simple understanding, so also he has an unchangeable choice. Accordingly, he is either not fixed upon evil at all, or, if he is fixed on evil, is fixed so immutably. Hence, his sin is not subject to expiation. Since, then, the chief cause of the divine incarnation appears to be the expiation of sin, as divine Scripture teaches us, it was more fitting that God assume a human than an angelic nature. Second, the assumption of the creature by God is in person, not in nature-as the foregoing makes clear. It was, therefore, more suitable to assume the human than the angelic nature because in man the nature is other than the person, for man is composite of matter and form; but this is not so in the angel, who is immaterial. Third, the angel, in what is proper to his nature, is closer to the knowledge of God than man is whose knowledge arises from the senses. Therefore, it was sufficient for the angel to be intelligibly instructed by God regarding divine truth. But the condition of man required that God instruct man sensibly about Himself as Man. This was done by the Incarnation. Then, again, the very distance of man from God seemed more repugnant to the divine enjoyment. Therefore, man needed to be assumed by God more than an angel did, that man’s hope for beatitude be stimulated. Lastly, man, since he is the term of creatures, presupposing, so to say, all other creatures in the natural order of generation, is suitably united to the first principle of things to finish a kind of cycle in the perfection of things.