Commentaria in Summam contra Gentiles, Liber IV

Having proved that the Holy Spirit is God, St. Thomas wishes to show that He is also a subsisting person¹, against those who say that He is the divinity of the Father and of the Son, and against those who say that He is some accidental perfection of the mind, namely wisdom or charity, or something of this sort. For it is shown that He is not something of this sort; and it is argued, first, that He is not an accidental form; second, that He is not the divinity of the Father and of the Son².

I. The first is shown in two ways. First. The Holy Spirit works according to the choice of His own will, as is clear from what was said above³. But accidental forms do not properly work, but rather he who has them uses them according to his own choice. Therefore etc.

Second. The Holy Spirit is the cause of all the perfections of the human mind, as is clear in Rom. 5, The charity of God, etc., and 1 Cor. 12, To another by the Spirit. Therefore etc.

II. The second point, however—namely, that by the name of the Holy Spirit the essence of the Father and of the Son is not designated as though He were not personally distinguished from either—is shown in three ways.

First. The Holy Spirit proceeds from the Father, John 15; and receives from the Son, John 16. But neither of these belongs to the divine essence. Therefore etc.

Second. Sacred Scripture manifestly speaks of the Holy Spirit as of a subsisting divine person, as is clear in Acts 13 and 15. Therefore etc.

Third. The Holy Spirit is numbered together with the Father and the Son, which are subsisting persons and of the divine nature. Therefore etc. — The antecedent is proved from what is said in the last chapter of Matt., Going therefore, etc.; and the last chapter of 2 Cor., The grace of our Lord, etc.; and the last chapter of 1 John, There are three, etc.

2. If someone should say that the Holy Spirit is one thing and the Spirit of God another—for in some of the aforementioned authorities He is named the Spirit of God, but in others the Holy Spirit—it is manifestly shown that the Spirit of God and the Holy Spirit are the same, from the argumentation of the Apostle in 1 Cor. 2, and from the fact that where in Matt. 10 it says, The Spirit of your Father, Mark says, The Holy Spirit.

III. From these things St. Thomas infers that we are not compelled to say that the Holy Spirit's filling the minds of the saints and dwelling in them is to be understood in the same way as the devil is said to fill and dwell in some persons, John 13 and Acts 5. Because the devil, since he is a creature, does not fill anyone nor dwell in them by a participation of himself or through his own substance, but only through the effect of his malice, as is found in Acts 13, O full, etc. But the Holy Spirit, since He is God, dwells in the mind through His own substance, and by a participation of Himself makes men good. — Nor is it thereby ruled out that He fills the minds of the saints through the effect of His power.

IV. Concerning this last statement, it must be considered that a spiritual substance can be understood to fill the mind of man in two ways: in one way, through the effect of its power, namely because some effect of its power is caused by it in the mind; in another way, through its own substance. In the first way, a created spiritual substance can fill and inhabit the mind of man, because it can cause some effect in it by acting directly or indirectly, as was shown in the preceding chapters⁴; but it cannot inhabit it in the second way. God, however, can fill the mind of man in both ways. And therefore, after St. Thomas said that the Holy Spirit according to His substance inhabits the minds of the saints by giving them being, as was shown in the preceding chapter, he added that it is not thereby excluded that He inhabits them through the effect of His power; for virtues are caused in the mind by God.

V. But then a doubt arises. For a spiritual substance is there according to its substance where it operates⁵. If therefore it operates something in the minds of the saints, namely by illuminating or by doing something else, it follows that it is in the minds of the saints according to its substance. Therefore not only through the effect of its power.

For the solution to this, it must be noted, from the doctrine of St. Thomas in II Sent., d. 8, a. 5, ad 3, that, since to be within something is to be within its limits, according as a spiritual substance is within the limits of something, so it is said to be within it. But since the limit of a thing is twofold, namely the limit of bodily quantity, as is found in bodies, and the limit of essence, as is found in every creature: a spiritual substance can be within the limits of bodily quantity, because it can operate within them; but it cannot be within the limits of essence, neither as a part nor as a power giving being, because being, especially of spiritual things, is through creation, as was shown in the preceding⁶. Therefore a spiritual substance can be within bodies, and fill and inhabit those bodies according to the limits of bodily quantity. But it cannot be within the human mind, which has no limits of bodily quantity, but only of essence, within which only He who gives being to the mind enters and operates, namely God Himself; although a created substance can also operate something extrinsically around the mind itself, which is to be in it through the effect of its power.

When therefore it is said that a spiritual substance is there according to its substance where it operates: — it is answered that, if being there and operating there are taken proportionally, then the proposition is universally true. For a spiritual substance, if it operates in something as operating within its limits, is within it and inhabits it. Likewise, if it is in something as extrinsically operating something in it, it is extrinsically in it; which nonetheless is improperly for one substance to be in another. Hence also, if the minor premise is subsumed in this sense, that a created substance operates something in the minds of the saints as operating within their limits, it is false. But if it is subsumed in the other sense, namely that it operates in the minds of the saints as operating extrinsically and not within the essence, then it is true; and the conclusion is true, namely that a created substance is according to its substance in the minds of the saints as something extrinsic; which nonetheless, as was said, is spoken improperly. — But if the said proposition is taken in this sense, that in whatever thing a spiritual substance operates in any way whatsoever (whether, I say, by acting within the limits of the thing, or by operating something extrinsically), it is within it and fills or inhabits it: it is false.

Now, to be there where it operates is posited by the doctors in this sense: that it is according to its substance in that place in which the body is upon which it operates. And thus it possesses truth.