Augustine opens Book 1 by invoking God’s aid in the interpretation of scripture, and in the writing of On Christian Doctrine. He tells readers that scripture is full of signs and messages both literal and figurative; correct interpretation depends upon knowing the proper meaning of a passage and revealing that meaning to others. Augustine notes that there are differences between the temporal world and the spiritual world, likening the believer’s life on the earth to a journey that an exile undertakes far from his native land. As an exile, the believer is to keep in mind his true destination (heaven), and to learn how to cherish things that are spiritual and eternal over the things which are temporary and worthless in comparison.

Augustine celebrates the power of words by discussing how speech passes away as soon as it is spoken, but the written word endures, and scripture is God’s word in physical form. He contrasts the sinfulness of man with the goodness of Jesus and offers a series of contrasts between sin and redemption, vice and virtue. He also stresses the importance of repentance for all believers, as a Christian who does not believe his sins can be pardoned is at risk of losing his faith entirely.