On Christian Doctrine - Augustine of Hippo, D.W. Robertson Jr. In contrast to the unwieldy and meandering City of God, Augustine’s four books On Christian Doctrine are notably focused in comparison. Augustine seems to be at his best when he can let his rhetorical skills breathe. His arguments stay rooted in his fundamental belief in biblical truth, but at least here he engages in active interpretation. The entire last book is dedicated to honing skills to distinguish between literal and figurative biblical passages. He seeks for allegory in much of the Old Testament.

Interestingly, Augustine speaks little of morality in his books On Christian Doctrine. There is but one purpose in our being for God- “He does not enjoy us but uses us.” Bk. 1, XXXI. In return, “He has mercy on us that we may enjoy him, and we have mercy on our neighbor so that we may enjoy Him.” Bk. 1, XXX. Unlike the Greek and Roman thinkers of before who sought the ways of righteous living to obtain eudaimon (spiritual happiness), Augustine strives for perfecting obedience and charity. Interpretation and study of biblical teachings lead the studious past the obscurity brought by original sin and into a fuller understanding of God’s wishes. Advancements in thought by philosophers before are used, but selectively.
If those who are called philosophers, especially the Platonists, have said things which are indeed true and are well accommodated to our faith, they should not be feared; rather, what they have said should be taken from them as from unjust possessors and converted to our use. Bk. 2, XL.
Augustine’s life of humility and quest for “faith, love and charity” strikes a chord for all who pursue decency. However, all builds upon that faith in biblical authority. Where the philosophers of prior centuries had faith in the existence of some abstract value, or even just man’s ability to achieve eudaimon through critical thought, Augustine places his faith in a collection of writings serving as an encoded blueprint for human action and thought.