This thesis is based on a careful reading and analysis of St. Augustine's "De Trinitate". Concentrating on the interpretation of essential passages much more than on the evaluation and discussion of secondary material, it deals with St. Augustines doctrine of the trinity with regard to the following two aspects: On the one hand, it tries to understand St. Augustine's attempt to formulate the doctrine of the trinity as it was presented to him in the orthodox teaching of his church (i.e. the Nicene Creed). His main problems were how to relate unity and trinity in God to each other as well as how to combine the innertrinitarian and the extratrinitarian aspect. The author comes to the conclusion that the contents of St. Augustin's teaching is drawn from the extratrinitarian aspect, i.e. from the way how God reveals himself to man in the course of the history of salvation, much more than one would generally think of a theologian of the Western Church (Ch. 2). On the other hand, looking at the second half of "De Trinitate" (book VIII-XV), the thesis considers the important fact that St. Augustine did not only want to formulate a dogmatical issue but also to show the possibility of man to understand, and thus draw nearer to, the trinity in a personal and existential act of knowing. To explain this, some main lines of St. Augustine's theology had to be considered in their relation to this topic: his teaching of God as the supreme being and creator of the world (Ch. 3), his teaching of man as the supreme of God's creatures, as "imago dei", and as the sinner who is unconsciously dependent on God's preserving grace (Ch. 4), and, finally, some aspects of his christology (Ch, 5), These two parts of the thesis are preceded by an introductory chapter (Ch, 1) which looks at St. Augustine from the point of view of his biography, of the history of doctrine, and of his philosophical and theological preconditions
