According to Anglican Bishop Rowan Williams, the final book of St. Augustine of Hippo’s De Trinitate (On the Trinity) has been described as “one of Augustine’s supreme theological achievements.” Indeed, the book begins by summarizing the prior fourteen books, and by summarizing, it then pushes forward into its last examination of the Trinity. Although there are multiple themes within book 15, the primary considerations of interest involve the question of Trinitarian relations. Indeed, how does St. Augustine understand the “relation” of Father, Son, and Holy Spirit in book 15 of De Trinitate? Augustine speaks of “the unity and equality of that highest Trinity… which is in all things equal, being also equally in its own nature unchangeable, and invisible, and everywhere present, works indivisibly” (5). The Trinity as a concept can be said to have been around from the start. In the 1st century AD, we may note that Philo of Alexandria, a Jewish philosopher, spoke of God, his Word and his Spirit – as the Spirit of God is seen as early as Genesis 1:2, and different passages in Genesis seem to suggest a plurality in God’s nature (Genesis 1:26; 3:22; 11:7, etc.). Other passages in the Hebrew Bible and in the New Testament suggest this plurality – such as the Great Commission in Matthew 28.
As history progressed and heresies arose, a more refined and defined notion of the Trinity needed to come about. Although the Trinity was discussed by writers such as Tertullian (AD 200) and others, one of the earliest understandings of the Trinity is seen in the Nicene Creed. This is all rather relevant to St. Augustine, because this is where Augustine comes from. Indeed, at one point Augustine writes, “God of God, Light of Light, Wisdom of Wisdom, Essence of Essence” (23), which is essentially an indirect quote from the Nicene Creed. With this in mind, Trinitarian understandings in Augustinian thought can be better grasped. He makes references throughout to the Trinity that we may pick up on and finally compile into a coherent understanding of Augustine’s view. For example, he writes that the Son “knows all that the Father knows” (23), that “therefore not God the Father, not the Holy Spirit, not the Trinity itself, but the Son only, which is the Word of God, was made flesh; although the Trinity was the maker” (20) and that “we speak that which is true; for we say what we know, for we know that we lied. But that Word which is God, and can do more than we, cannot do this. For it ‘can do nothing except what it sees the Father do;’ and it ‘speaks not of itself,’ but it has from the Father all that it speaks, since the father speaks it in a special way; and the great might of that Word is that it cannot lie, because there cannot be there ‘yea and nay,’ but ‘yea yea, nay nay’” (24).
From these passages, we can glean Augustine’s thought that the Son is equal to the Father but that only the Son is the Word of God, and that God cannot lie – and as the Son does as the Father does, and the Father cannot lie, therefore the Son does not lie either. There is therefore a strong connection between the Father and the Son, and the Father has a set role just as the Son has a set role as the Word of God and the one who became incarnate as man. But what of the Holy Spirit? According to Augustine, “the Holy Spirit, according to the Holy Scriptures, is neither of the Father alone, nor of the Son alone, but of both; and so intimates to us a mutual love, where with the Father and the Son reciprocally love one another” (27). From this, Augustine argues that although as St. John says, “God is love,” it remains “to be inquired whether God the Father is love, or God the Son, or God the Holy Ghost, or the Trinity itself which is God” (27). But, as he says, the Father is God, the Son is God and the Holy Spirit is God – three yet one.
Yet Augustine goes on to say that “it is not to no purpose that in this Trinity the Son and none other is called the Word of God, and the Holy Spirit and none other the Gift of God, and God the Father alone is He from whom the Word is born, and from whom the Holy Spirit principally proceeds” (29). Therefore, the Holy Spirit is the Spirit of both the Father and of the Son. Yet if he is the Spirit of the Father, does this not also make the Holy Spirit the Father of the Son, and the Son therefore the Son of the Holy Spirit? This is unreasonable, evidently, and it seems clear that Augustine’s primary argument here is that each person of the Trinity has a distinct role, although God remains one. He suggests that the Spirit represents both the Gift of God and the Love of God, just as the Son is the Word of God, for if “any one of the three is to be specially called Love, what more fitting than that it should be the Holy Spirit?” (29). He indeed believes that both “God the Father and God the Son can be called Love” (30), but that the Holy Spirit ought to be called the Love of God. There are a variety of reasons listed, but he concludes by noting that the “Apostle Paul, too, says, ‘The love of God is shed abroad in our hearts by the Holy Ghost, which is given unto us’” (31).
In this understanding, then, the Holy Spirit can be understood as the Love of God. He argues that the Spirit would not be called in the New Testament the “Gift of God” unless He was also the Love of God. From this, Augustine moves on to trying to grapple with the matter of generation and procession, and “why the Holy Spirit is not a Son, although He proceeds from the Father” (45). He notes that the Holy Spirit is both the Spirit of the Son and the Spirit of the Father, which is concluded from a number of passages where the Son evidently sends the Spirit and breaths the Spirit into others. Yet if is sent by both the Son and the Father, we may wonder, is the Holy Spirit not the Son of the Father and the Son of the Son? To this, Augustine adds that it “is most difficult to distinguish generation from procession in that co-eternal, and equal, and incorporeal, and ineffably unchangeable and indivisible Trinity” (48), and “the Holy Spirit is not said to be born, but rather to proceed; since if He, too, was called a Son, He would certainly be called a Son of both, which is most absurd, since no one is son of two, save of father and mother” (48). He follows this argument by saying that even humans do not proceed at the same time from both the father and the mother. Instead, a human proceeds from the father into the mother, and then from the mother into the present life (48). Augustine finds the suggestion absurd that the Spirit could be begotten, and says that “you will see how the birth of the Word of God differs from the procession of the Gift of God, on account of which the only-begotten Son did not say that the Holy Spirit is begotten of the Father, otherwise He would be His brother, but that He proceeds from Him” (50).
Augustinian thinking on the relationship of the Trinity can thus be summed up as Lover, Love and Beloved. Elsewhere he uses these terms to describe the relationship, but if the Father is the Father, the Son is the Word of God and the Holy Spirit is both the Gift of God and the Love of God, then the Father is the Lover, the Spirit is Love itself and the Son is the Beloved, which lines up with the Father’s words at the baptism of Jesus. The issue between procession and generation caused a great deal of controversy at various points in Church History, but here Augustine seems to say that the Son proceeds from the Father, and the Spirit proceeds from the Father and the Son, whereas the Father proceeds from neither, and the Son is generated by the Father – begotten, not created. Book 15 can rightly be called his seminal work on the Trinity, and it will remain a treasure among Trinitarian thought for ages to come. Certainly, the Trinity is perhaps the most complex and unfathomable mysteries of the Christian faith, yet it also remains the most dazzling and the most tantalizing, and the contribution of Book 15 from St. Augustine is one to bear in mind: each person in the Trinity has a role, just as we are each assigned a role on this world.