The thesis is concerned with use of the philosophical categories of substance and relation in the trinitary theology of St. Augustine of Hippo. The starting point is two passages: Conf. 4,16; De Trin. 5,2,3.
In Conf. 4,16, St. Augustine explains that God is not included in the category of substance as God is simple and unchangeable. In De Trin. 5,2,3 on the other hand, St. Augustine states that God is with- out doubt substance or essence, ousia. Because God is not included in the category of substance; yet God certainly is substance. How can the two statements be reconciled? Is there an aporia here? We will attempt to clear up this somewhat paradoxical circumstance.
In Chap. 1 we see how it relates to the possibility of talking about God, as God has to be ineffable at the same time. We identify a number of rules St. Augustine applied to theological discourse. An affirmative theology emerges which is nonetheless capable of ensuring that God cannot be mentioned and cannot be understood.
Chap. 2 is dedicated to the theme of essence (substance). We note two definitions: 1) quod est; 2) qua est. We see that both coincide in God, because ʻGod is that which He hasʼ (quod habet hoc est). In Chap. 3 we reflect on the fact that God is a Trinity. This circumstances significantly complicates the theological picture.
In Chap. 4 we attempt a final reflection and discuss ʻaporiaʼ in St. Augustine
