Arguments over the filioque, the arguments about which begin this week, divide the Church. That is unfortunate, regardless which side you take. Why argue irreconcilably over a mystery when the world delights in it? Brace yourselves. The going is not easy.
1 We find some who make this mistake about the procession of the Holy Spirit: they say the Holy Spirit does not proceed from the Son. For this reason we must show that the Holy Spirit does proceed from the Son.
2 It is manifest in sacred Scripture that the Holy Spirit is the Spirit of the Son, for Romans (8:9) says: “If any man have not the Spirit of Christ, he is none of His.” But that one might not be able to say that the Spirit that proceeds from the Father is one, and the Son’s Spirit another, it is shown from the words of the same Apostle that the Holy Spirit of the Father and of the Son is identified.
For the words just cited, “If any man have not the Spirit of Christ, he is none of His,” the Apostle added after he had said: “If so be that the Spirit of God dwell in us,” and so forth. But one cannot say that the Holy Spirit is the Spirit of Christ merely because He had Him as man, according to the words of Luke (4:1): “Jesus being full of the Holy Spirit, returned from the Jordan.” For one reads in Galatians (4:6): “Because you are sons, God has sent the Spirit of His Son into your hearts, crying: Abba (Father).”
The Holy Spirit, therefore, makes us the sons of God precisely because He is the Spirit of the Son of God. But we are made the adoptive sons of God by assimilation to the natural Son of God, as Romans (8:29) has it: “Whom He foreknew, He also predestined to be made conformable to the image of His Son, that He might be the firstborn amongst many brethren.” Thus, then, is the Holy Spirit the Spirit of Christ: so far as He is God’s natural Son. But there is no relation in accord with which the Holy Spirit can be called the Spirit of the Son of God except a relation of origin, for this is the only distinction we find in divinity. Therefore, one must say that the Holy Spirit is the Son’s Spirit by proceeding from Him.
3 The Holy Spirit, again, is sent by the Son; consider John (15:26): “When the Paraclete cometh, whom I will send you from the Father.” But whoever sends has an authority over the one sent. One must, then, say that the Son has an authority in regard to the Holy Spirit: not, of course, that of being master or being greater, but in accord with origin only. In this wise, then, the Holy Spirit is from the Son.
Now, let one say that the Son is sent by the Holy Spirit as well, because we read in Luke (4:18-21) that our Lord said Isaiah’s words (61:1) were fulfilled in Him: “The Spirit of the Lord is upon Me, He has sent Me to preach the gospel to the poor.” But consideration must be given this: the Son is sent by the Holy Spirit in accord with the assumed nature. But the Holy Spirit has not assumed a created nature, so that in accord with it He can be called sent by the Son, or so as to give the Son authority in His regard. Therefore, this remains: it is considered as an eternal person that the Son has authority over the Holy Spirit.
4 There is more. In John (16:14-15), the Son says of the Holy Spirit: “He shall glorify Me because He shall receive of Mine.” Of course, this cannot be said: He receives what is the Son’s, but does not receive from the Son; by saying, for instance, that He receives the Son’s divine essence from the Father. Hence, our Lord adds: “All things whatsoever the Father has are mine. Therefore, I said that He shall receive of Mine.” For, if all things which are the Father’s are the Son’s as well, the Father’s authority as principle of the Holy Spirit must be the Son’s as well. Therefore, just as the Holy Spirit receives what is the Father’s from the Father, so He receives what is the Son’s from the Son.
5 Here one can also introduce the testimonies of the Doctors of the Church, the Greeks included. Athanasius says: “The Holy Spirit is from the Father and the Son—not made, not created, not begotten, but proceeding.” Cyril, too, in his epistle received by the Council of Chalcedon, says: “The Spirit of the truth is named and is the Spirit of the Truth and flows from Him just as, indeed, from God the Father.” Didymus also says in his book On the Holy Spirit: “The Son is nothing else than what is given to Him by the Father, and the substance of the Holy Spirit is no other than that given Him by the Son.”
Of course, it is ridiculous that some concede that the Holy Spirit “is from the Son” or “flows from the Son” but does not “proceed from. Him.” For the verb “to proceed,” among all those which refer to origin, turns up most commonly; for, if anything is in any way at all from something, we say it proceeds from that thing. And since divinity is better designated by what is common than by what is special, in the origin of the divine persons the verb proceeding is the most suitable. And so, if one concedes that the Holy Spirit “is from the Son” or “flows from the Son,” it follows that “He proceeds from the Son.”
6 There is this, too, in the determination of the Fifth Council: “In all matters we follow the holy Fathers and Doctors of the Church: Athanasius, Hilary, Basil, Gregory the theologian, and Gregory of Nyssa, Ambrose, Augustine, Theophilus, John of Constantinople, Cyril, Leo, Proclus; and we accept what they have set down on the correct belief and the condemnation of heretics.” But it is manifest from many testimonies of Augustine, especially his On the Trinity and his Exposition of John, that the Holy Spirit is from the Son. It must, then, be conceded that the Holy Spirit is from the Son just as He is from the Father.
7 This is also clarified by straight reasoning. For among things, with the material distinction gone (and in the divine Persons such can have no place), one discovers no differentiation except by some opposition. For things which have no opposition to one another can be simultaneously in something identical; thus, no distinction can be caused by them. Take white and triangular. Although they are diverse, they can, because they are not opposed, be in an identical thing. But one must set down, according to the documents of the Catholic faith, that the Holy Spirit is distinct from the Son; otherwise, there would not be a Trinity, but a duality of Persons. Therefore, a distinction of this kind must take place through some opposition.
But it is not the opposition of affirmation and negation. for such is the distinction of being from non-being. Nor is it the opposition of privation and habit, for such is the distinction of the perfect from the imperfect. Neither is it the opposition of contrariety, for such is the distinction of diversity of form. For contrariety as philosophers teach, is a “difference following on form.” And this difference is not suited to the divine Persons, since their form is one, just as their essence is. Hence, the Apostle says, speaking of the Son, “being in the form of God” (Phil. 2:6), the form, namely, of the Father.
Therefore, the conclusion remains that one divine Person is not distinguished from another except by the opposition of relation: thus, the Son is distinguished from the Father consequently to the relative opposition of father and son.
It is because in the divine Persons there can be no relative opposition except, consequently, on origin. For a relative opposition is founded on quantity—say the double or the half; or on action and passion, say master and servant, mover and moved, father and son. Further, among the relative oppositions founded on quantity, some are founded on diversity of quantity—say the double and the half, the greater and the lesser, some on unity itself—say identity, which means one in substance, and equality, which means one in quantity, and similarity, which means one in quality.
The divine Persons, therefore, cannot be distinguished by relations founded on diversity of quantity, because this would take away the equality of the three Persons. Nor, again, by the relations which are founded on unity, because relations of this kind cause no distinction; rather, in them one finds more of what pertains to agreement, although some of them may presuppose a distinction. In all relations founded on action and passion, however, there is always one of the two which is a subject and unequal in power to the other; here, exception is made only for the relations of origin, and in such there is no lesser indicated, because one finds there something producing that which is similar and equal to itself in nature and power.
The conclusion, therefore, must be that the divine Persons cannot be distinguished except by relative opposition in origin. Therefore, if the Holy Spirit is distinguished from the Son, He is necessarily from the Son, for we do not say that the Son is from the Holy Spirit, since the Holy Spirit is, rather, said to be of the Son and given by the Son.
8 Again, the Son is from the Father and so is the Holy Spirit. Therefore, the Father must be related both to the Son and the Holy Spirit as a principle to that which is from the principle. He is related to the Son by reason of paternity, but not to the Holy Spirit; for then the Holy Spirit would be the Son, because paternity is not said except of a son. There must, then, be another relation in the Father by which He is related to the Holy Spirit; and spiration is its name.
In the same way, since there is in the Son a relation by which He is related to the Father, the name of which is sonship, there must also be in the Holy Spirit another relation by which He is related to the Father, and this is called procession. And thus, in accord with the origin of the Son from the Father, there are two relations, one in the originator, the other in the originated: to wit, paternity and sonship; and there are two others in reference to the Holy Spirit: namely, spiration and procession. Therefore, paternity and spiration do not constitute two Persons, but pertain to the one Person of the Father, for they have no opposition to one another. Therefore, neither would sonship and procession constitute two persons, but would pertain to one, unless they had an opposition to one another. But there is no opposition to assign save that by way of origin. Hence, there must be an opposition of origin between the Son and the Holy Spirit so that the one is from the other.
9 What is more, when things come together by something common to them, they must, if they are to be distinguished, be distinguished by differences which belong per se and not accidentally to that common thing. Thus, man and horse meet in animal, and are distinguished from one another not by black and white, which are related accidentally to animal, but by rational and irrational, which are per se pertinent to animal.
This is because animal is what has soul [animam], and this must be distinguished by having this or that kind of soul; say, rational or irrational. Now, manifestly, the Son and the Holy Spirit agree in their being from another, since each is from the Father. And in this the Father suitably differs from each, in that He can have no birth-origin [innascibilis]. Therefore, if the Holy Spirit be distinguished from the Son, this must take place by differences which per se divide this being from another. And such, indeed, can only be differences of the same genus—namely, pertaining to origin—so that one of them is from the other. One concludes, then, that the distinction of the Holy Spirit from the Son requires that He be from the Son.
10 Let one say, further, that the Holy Spirit is distinguished from the Son not because He is from the Son, but by reason of their differing origin from the Father. The difficulty really returns to the same point, for, if the Holy Spirit is other than the Son, the origin or procession of each must be other. But two origins cannot be distinguished except by term, or by principle, or by subject.
Thus, the origin of a horse differs from the origin of a cow by way of term, in that these two origins have their terms in natures diverse in species. There is difference by way of principle if we suppose that some animals in the same species are generated by the active power of the sun alone, and some others along with this power by the active power of the seed. There is difference by way of subject when the generation of this horse differs from that as the nature of the species is received in diverse matters.
But this distinction on the part of subject can have no place in the divine Persons, since they are entirely immaterial. In the same way, also, on the part of the term, granting one may speak so, there can be no distinction of processions. For the divine nature, one and the same, which the Son receives by His birth, the Holy Spirit receives by His proceeding. It remains, therefore, that the distinction of each origin can be only on the part of the principle. Manifestly, of course, the principle of the origin of the Son is the Father alone. If, therefore, the principle of the procession of the Holy Spirit is the Father alone, the procession of the Holy Spirit will not be other than the generation of the Son; thus, neither will the Holy Spirit be distinct from the Son. Therefore, that there may be otherness in processions and otherness in those proceeding, one of necessity says that the Holy Spirit is not from the Father alone, but from the Father and the Son.
11 But, again, if one says that the processions differ in principle, in that the Father produces the Son by way of intellect as Word, and the Holy Spirit by way of will as Love, it will be necessary to say that in accord with a difference of intellect and will in God the Father the two processions and the two proceeding are to be distinguished. Will and intellect in God the Father are not distinguished really, but only rationally, as was shown in Book I. It follows, then, that the two processions and the two proceeding differ only rationally.
Now, things which differ only rationally are predicated of each other: it will be truly said that the divine intellect is the divine will, and conversely. Therefore, it will be true to say that the Holy Spirit is the Son, and conversely. This is the Sabellian impiety. Therefore, it does not suffice for the distinction of the Holy Spirit and the Son to say that the Son proceeds by way of intellect and the Holy Spirit by way of will, unless along with this one says the Holy Spirit is from the Son.
12 There is more. From the very fact of saying that the Holy Spirit proceeds by way of will and the Son by way of intellect it follows that the Holy Spirit is from the Son. For love proceeds from a word: we are able to love nothing but that which a word of the heart conceives.
13 Again, if one considers the diverse species of things, a certain order appears in them: the living are above the nonliving; animals are above plants; and man is above the other animals. And in each of these, different grades are discovered according to different species; hence, even Plato said that the species of things are numbers, which are varied in species by the addition and subtraction of unity. Hence, in immaterial substances there can be no distinction except that of order. But in the divine Persons who are entirely immaterial there can be no other order than that of origin. Therefore, there are not two Persons proceeding from one, unless one of those proceeds from a second. And thus, necessarily, the Holy Spirit proceeds from the Son.
14 Moreover, the Father and the Son, unity of essence considered, do not differ save in this: He is the Father and He is the Son. So, anything other than this is common to the Father and the Son. But to be the principle of the Holy Spirit is not included in the notion of paternity and of sonship, for it is one relation by which the Father is Father, and another by which He is the principle of the Holy Spirit, as was said above. Therefore, to be the principle of the Holy Spirit is common to the Father and the Son.
15 Furthermore, whenever one thing is not opposed to the essential intelligibility of another, there is no impossibility—unless, perhaps, accidentally—about their coming together. But to be the principle of the Holy Spirit is not contrary to the intelligibility of the Son: not in so far as He is God, because the Father is the principle of the Holy Spirit; nor in so far as He is Son, because the procession of the Holy Spirit is other than that of the Son. It is, of course, not repugnant to have what is from a principle according to one procession he the principle of another procession. It follows, then, that it is not impossible for the Son to be the principle of the Holy Spirit. But that which is not impossible can be. “In divinity being and possibility do not differ.” Therefore, the Son is the principle of the Holy Spirit.