Augustine’s faith was essentially a thinking faith, endeavouring to bring together the belief of his heart and the abilities of his mind. This is well illustrated by the fact that his favourite verse from scripture was a [mis]quotation from Isaiah 7:9, ‘If you do not believe, then you will not understand.’ Faith seeks understanding: faith first, understanding afterwards. This is the leitmotif of his 15-book work, On the Trinity, and is especially prominent towards the end of book 7.
We are better informed about Augustine than about any other figure in the ancient world, and this is above all because he did something which no other ancient writer, with the possible exception of the great orator and letter writer Cicero, ever did: he wrote an autobiography. The Greeks abhorred autobiography; however, Augustine’s Confessions, composed between 397 and 400, began a trend that surfaced above all in Rousseau and later in John Henry Newman with his Apologia pro vita sua.