In this study I have proposed that the soliloquy, or inner dialogue, was Augustine's major type of spiritual exercise in works written between 386 and 400. This literary form was also employed in works written at later dates, for example in the Confessions, On the Trinity, and The City of God. His use of inner dialogue thus illustrates the continuity in his approach to metaphysical questions during the period in which theology replaced philosophy as the major discipline occupying his scholarly interests.

Augustine worked within an ancient tradition of such exercises which included such authors as Plato, Cicero, Seneca, and Plotinus. He drew inspiration from the Psalms, gospels, and Pauline epistles, and from exemplary Christian life histories, for example those of St. Antony, Paulinus of Nola, and his friend, Alypius, the remnants of whose vita may have been incorporated into the Confessions. Given the eclectic nature of his education, he was able to view the formal features of the soliloquy in the perspective of three disciplines, namely rhetoric, philosophy, and theology. But it was the philosophical dimension which chiefly interested him in the critical years between the writing of his dialogues and the Confessions, as well as later works, such as On the Trinity, in which books eight to fifteen revisited philosophical problems taken up at Milan, Cassiciacum, and Rome. He called this form of inquiry the soliloquium and it was he who brought this type of dialogue into the orbit of Western philosophical tradition.