What is the main conflict in On Christian Doctrine by Saint, Bishop of Hippo Augustine?

De Doctrina Christiana was written by the great philosopher, theologian and Bishop of Milan, Augustine of Hippo, around the beginning of the fifth century A.D. He wrote it for a variety of reasons, but three predominate: (i) he wanted to convince those who thought they could simply divine the meaning of Scripture to study and pay heed to interpretation, (ii) he wanted to teach principles of Scriptural interpretation and encourage the study of subjects that aid Scriptural interpretation, and (iii) he wanted to teach Christian speakers about the skills and practices of a good Christian orator. The writing of De Doctrina Christiana was halted when Augustine became Bishop of Milan, but he later resumed it, so the book has a certain divide in