This year, as part of my devotional studies, I am working my way through Augustine’s magisterial volume On the Trinity. I am hoping to provide some reflection and analysis here as I work through it.
Today, I was reading 2.1.4 and 2.1.5 today (99-100) and came upon something I think is a very fruitful discussion. Augustine, toward the beginning of this chapter, discussed that there is a particular rule which was informally utilized by various commentators and theologians. Roughly speaking, the rule was that if the text speaks of the Son as less than the Father, it is referring to the “form of a servant” IE according to humanity. If the text speaks of the Son as equal to the Father, it is a reference to the “form of God” IE according to divinity.
He also points out that some unclear passages which speak of the Son in a way that refers to the fact that the Son is from the Father, and do not fit either of the above two categories.
There are, however, some statements in the divine utterances of such a kind that it is uncertain which rule should be applied to them; should it be the one by which we take the Son as less than the Father in the created nature he took on, or the one by which we take him as equal to the Father, while still deriving from him his being God from God, light from light? (2.1.2)
He uses these passages to ground the eternal processions of the Son and Holy Spirit. Of particular note is John 5:26 and 5:19.
For as the Father has life in himself, so he has granted the Son also to have life in himself. (5:26, ESV)
So Jesus said to them, “Truly, truly, I say to you, the Son can do nothing of his own accord, but only what he sees the Father doing. For whatever the Father does, that the Son does likewise.(5:19, ESV)
Augustine brilliantly uses the latter to show that the external works of the Trinity are one. I will leave that discussion for a later post. But the former is a verse that has always puzzled me. The verse is arguably talking about the divine attribute of aseity, but how can in-him-self-ness be granted to you? Doesn’t that defeat the whole point of aseity?
So the reason for these statements can only be that the life of the Son is unchanging like the Father’s, and yet it is from the Father (2.1.3)
The Son is indeed a se, but his aseity is from the very nature which comes from the Father. That is, since the Son’s personal origin is that he is begotten of the Father, he gets everything he has and is from the Father. That is why the Nicene Creed, which Augustine is referencing here, says that the Son is “God from God, light from light, true God from true God.” It is also the reason that the Athanasian Creed indicates that although each person considered as a person is a given attribute —Aseity, Omnipotence, etc.— that there is only one attribute shared among the persons.
Therefore, just as He gave the Son life (Jn 5:26) means nothing else than “He begot the Son who is his life… (2.1.4)
Understanding this is vital for the Reformed to, because this theology would develop into a doctrine in Roman Catholic thought —especially under Aquinas— where the nature of the Son is actually communicated to the Son by the Father such that it is practically a second numerical nature. Calvin, however, would postulate a different formula which better retains the numerical singularity of the divine nature. Some accuse Calvin of implicitly denying eternal generation —and consequently of eternal procession— but in actuality, this is simply a proper recovery of what Augustine is saying here.
Augustine then takes this same approach and applies it to the procession of the Holy Spirit.
And just as the Son is not made less than the Father by his saying, The Son cannot do anything of himself except what he sees the Father doing (Jn 5:19) […] so her it does not make the Holy Spirit less to say of him, He will not speak from himself but whatever he hears he will speak (Jn 16:13). This is said in virtue of his proceeding from the Father. (2.1.5)
While I doubt that this kind of sophisticated reasoning will do much to convince the hardened Jehovah’s Witness… or EFS advocate for that matter… it goes a long way to demonstrate —using Scripture— that these eternal processions exist.
For a very helpful modern treatment of the subject, see Holmes, Christopher. The Holy Spirit. New Studies in Dogmatics. Grand Rapids: Zondervan, 2015. Holmes devotes 4 chapters —two each— specifically to the procession of the Holy Spirit as it is developed by Augustine and Aquinas in their commentaries and sermons on the Gospel of John.
 I am working from Augustine of Hippo. The Works of Saint Augustine. Edited by John Rotelle. Translated by Edmund Hill. Vol. 5. Hyde Park: New City, 1991. All citations will follow the numbering and pagination scheme for that version.
 Processions refer to the two relationships of origin which the Son and Spirit have with the Father. It is an unfortunate quirk of theological linguistics that the term Processions (plural) is used to describe these relationships while the term Procession (singular) is also used to describe the unique relationship of origin which the Spirit has with the Father (and or through the Son)
 Dr. K Scott Oliphint offers an excellent lecture regarding this that is available at the Reformed Forum site.