"The good of the grace of one soul is greater than the good of the nature of the whole universe"
- St Thomas Aquinas Ia IIa, q.24, a. 3, ad 2
|REALITY—A Synthesis Of Thomistic Thought
by Reginald Garrigou-Lagrange, O. P.
Third Part: The Blessed Trinity
On the subject of the Thomistic synthesis as regards the mystery of the Trinity, we will first examine what St. Thomas owes to St. Augustine, then the doctrine of St. Thomas himself on the divine processions and relations and persons, and on the notional acts of generation and spiration. This doctrine then will enable us to see better why the Blessed Trinity is unknowable by natural reason. Next we will study the law of appropriation, and lastly the manner of the Trinity's indwelling in the souls of the just. Throughout we will emphasize the principles which underlie the development of theological science
CH13: AUGUSTINE AND THOMAS
In his commentaries on the New Testament, St. Thomas carefully examined the principal texts regarding the Blessed Trinity, in the Synoptic Gospels, in the Gospel of St. John, and in the Epistles of St. Paul. He analyzes with special emphasis the formula of baptism, our Lord's discourse before His passion, and especially St. John's prologue. His guides throughout are the Fathers, Greek and Latin, who refuted Arianism and Sabellianism.
These scriptural studies led him to see clearly the part played by St. Augustine in penetrating into the meaning of our Lord's words on this supreme mystery. This debt of Thomas to Augustine must be our first study. We find here a very interesting and important chain of ideas. Unless we recall both the advantages and the difficulties presented by the Augustinian conception, we shall not be able to understand fully the teaching of St. Thomas.
Sabellius had denied real distinction of persons in the Trinity. Arius, on the other hand, had denied the divinity of the Son; Macedonius, that of the Holy Spirit. In refuting these opposite heresies, the Greek Fathers, resting on scriptural affirmation of three divine persons, had sought to show how this trinity of persons is to be harmonized with God's unity of nature. This harmony they found in the term "consubstantial," a term which by controversy grew more precise, and was definitively adopted by the Council of Nicaea. The Son, said the Greek Fathers, led particularly by St. Athanasius,  is consubstantial with the Father, because the Father who begets the Son communicates to that Son His own divine nature, not a mere participation in that nature. And since this Son is the Son of God, His redemptive merits have infinite value. And. the Holy Spirit, proceeding from the Father and the Son, is likewise God, consubstantial with the Father and the Son, without which consubstantiality He could not be the sanctifier of souls. .
Now these Greek Fathers thought of the divine processions rather as donations than as operations of the divine intelligence and the divine will. The Father, in begetting the Son, gives to that Son His own nature. And the Father and the Son give that divine nature to the Holy Spirit. The mode, they add, of this eternal generation and spiration is inscrutable. Further, following the order of the Apostles' Creed, they spoke of the Father as Creator, of the Son as Savior, of the Holy Spirit as Sanctifier. But their explanations left the road open to many questions.
Why are there two processions, and only two? How does the first procession differ from the second? Why is that first procession alone called generation? Why must there be one Son only? And why, in the Creed, is the Father alone called Creator, since creative power, being a characteristic of the divine nature, belongs also to the Son  and to the Holy Spirit? The Latin doctrine of appropriation is not found explicitly in the Greek Fathers.
St. Thomas, reading Augustine's work,  realized that this greatest of the Latin Fathers had taken a great step forward in the theology of the Trinity. St. Augustine's point of departure is the unity of God's nature, already demonstrated philosophically. Guided by revelation, he seeks the road leading from that unity of nature to the trinity of persons. This road, followed also by St. Thomas, is the inverse of that followed by the Greek Fathers.
In St. John's prologue, our Lord is called "the Word" and the "Only-begotten." These terms struck St. Augustine. Did they not offer an explanation of that generation which the Greek Fathers called inscrutable? The Son, proceeding from the Father, is called the Word. That divine Word is, not an exterior, but an interior word, a mental, intellectual word, spoken by the Father from all eternity. The Father begets the Son by an intellectual act, as our spirit conceives its own mental word.  But while our mental word is an accidental mode of our intellectual faculty, the divine word, like the divine thought, is substantial.  And while our spirit slowly and laboriously conceives its ideas, which are imperfect, limited, and necessarily manifold, to express the diverse aspects of reality, created and uncreated, the Father, on the contrary, conceives eternally one substantial Word, unique and adequate, true God of true God, perfect expression of all that God is and of all that God does and could do. Much light is thus thrown on the intimate mode of the Word's eternal generation. .
The saint also explains, in similar fashion, the eternal act of spiration.  The human soul, created to the image of God, is endowed with intelligence and with love. It not only understands the good, but also loves the good. These are its two highest faculties. If then the Only-begotten proceeds from the Father as the intellectual Word, we are led to think that the Holy Spirit proceeds from both by a procession of love, and that He is the terminus of this latter procession. Here, then, enter the divine relations.  The saint speaks thus: "It is demonstrated that not all predicates of God are substantial, but that some are relative, that is, as belonging to Him, not absolutely, but relatively to something other than Himself." The Father is Father by relation to the Son, the Son by relation to the Father, the Holy Spirit by relation to the Father and the Son.  This doctrine is the basis of Thomistic doctrine on the divine relations.
So far, then, we have the reason why there are two processions in God, and only two, and why the Holy Spirit proceeds, not only from the Father, but also from the Son, just as in us love proceeds from knowledge. St. Augustine, however, does not see why only the first procession is called generation, and why we are not to say that the Holy Spirit is begotten. On this point, and on many others, St. Augustine's doctrine awaits precision by St. Thomas.
A similar remark must be made on St. Augustine's doctrine concerning the question of appropriation. Starting from the philosophically demonstrated unity of God's nature, and not from the trinity of persons, he easily shows that not the Father alone is Creator, but also the Son and the Holy Spirit, since creative power is a characteristic of the divine nature, which is common to all three persons. This doctrine, through the course of centuries, becomes more precise by successive pronouncements of the Church.  St. Thomas is ever recurring to it. The three persons are one and the same principle of external operation. If then, in the Apostles' Creed, the Father is in particular called the Creator, He is so called by appropriation, by reason, that is, of the affinity between paternity and power. Similarly, the works of wisdom are appropriated to the Word, and those of sanctification to the Spirit of love. This theory of appropriation, initiated by St. Augustine,  finds final precision in St. Thomas,  and definitive formulation in the Council of Florence. .
Other difficulties still remain in St. Augustine's Trinitarian conception, difficulties which St. Thomas removes.  Here we note briefly the chief difficulties.
The generation of the Word is an intellective process. Now, since the intellective act is common to the three persons, it seems that generation, even to infinity, belongs to all three persons. St. Thomas answers. From the essential act of understanding, common to the three, we must distinguish the personal "act of speaking" (dictio): which is characteristic of the Father alone. .
A similar difficulty attends the second procession, which is the mode of love. Since all three persons love infinitely, each of them, it seems, should breathe forth another person, and so to infinity. But again, from that essential love which is common, we must distinguish, first, notional love, that is, active spiration, and secondly personal love, which is the Holy Spirit Himself. .
These distinctions are not to be found explicitly in St. Augustine. But in St. Thomas they appear as natural developments of St. Augustine's principles, in contrast to the conception prevalent in the Greek Fathers Let us note the chief advantages of this Augustino-Thomistic conception.
a) Starting from De Deo uno, it proceeds methodically, from what is better known to us to what is less knowable, the supernatural mystery of three divine persons.
b) It explains, by analogy with our own soul life, of mind and love, the number and characteristics of the divine processions, which the Greek Fathers declared to be inscrutable. Thus it gives the reason why there are two and only two processions, and why the Holy Spirit proceeds not only from the Father but also from the Son.
c) It shows more clearly why the three persons are but one single principle of operations ad extra, since divine activity derives from omnipotence, which is common to all three persons. Here lies also the reason why this mystery is naturally unknowable, since creative power is common to all three. .
These positive arguments of appropriateness show how far St. Augustine had progressed from the Greek conception, attained from a different viewpoint. The difficulties left unsurmounted by St. Augustine himself are due, not to deficient method, but to the sublimity of the mystery, whereas the difficulties in the Greek conception are due to imperfect method, which, instead of ascending from natural evidence to the mysterious, descends rather from the supernatural to the natural.
We will now examine the structure of De Trinitate as it appears in the Summa,  dwelling explicitly on the fundamental questions which virtually contain all the others. First, then, the divine processions.