Barnes, Michel Rene. The Power of God: Dunamis in Gregory of Nyssa’s Trinitarian Theology.
This book ties Radde-Galwitz’s work as the finest work on Gregory of Nyssa. Dunamis is a richly biblical term, even with its philosophical baggage. In early Greek philosophy it meant the affectivy capacity of the physis, having causal connotations (Barnes 7). But in Pre-Socratic philosophy this always referred to a material entity, which wouldn’t do for Christian thought.
The capacity-power was always linked “to the identity and existence of an existent” (10). Thesis (1): If the Father and Son manifest the same dunamis, then they share the same phusis (13).
Barnes has some informative chapters on how the pre-Socratics and Plato used “dunamis.” He then moves to post-apostolic discussions before he lands on Eunomius’s heretical taxonomy.
Eunomius’s Doctrine of the Trinity
Simple thesis: “agennetos” is the essence of God. God’s simplicity makes his essence identical with ingeneracy (176). God produces his Son not essentially, but by authority. Any essential production implies material compositeness. His term for production is “energia” and the product is “ergon.” he does not associate energia with dunamis. Energia is a causality which ceased to be when not productive (194).
Therefore, on Eunomius’s gloss, it is not simply that Jesus is a product of the Father. Rather, the Son is a product of the Activity of the Father. Arius’s Jesus was simply once removed from the Father. Eunomius’s is several times removed.
Gregory responds. Gregory uses “power” as a title of the divine nature, mainly in the phrase “transcendent power.” Not only is God properly beyond-being, but also his power is beyond-being. Gregory links power to God’s nature in the such that it is a capacity that produces (223).
It is the capacity to produce or create. If the power to create is a power, then it is connatural to God (234). If you separate the productive capacity from God’s nature–as Eunomius does–then you won’t have any signs of that nature (250).
Therefore, Key argument: “Differences in being are determined first, by the presence or absence of certain powers or properties, and second, by the way in which these powers or properties are united in the existent” (272). Sequence: Dunamis-energia-erga
Activity is always “activity produced by the power of an existent” (302). Activity presupposes power. Therefore, a hypostatized nature’s dunamis produces the energia, which results in the ergon.
This book sings and deserves widest possible reading, especially after the goofy Evangelical Subordinationist Trinity fiasco last year. My only criticism is that relatively little of the book was devoted to Gregory.