Book V follows the young Augustine from Carthage (where he finds his students too rowdy for his liking) to Rome (where he finds them too corrupt) and on to Milan, where he will remain until his conversion. Manichee beliefs begin to lose their luster for him during this period, and by the end of the Book he considers himself an unbaptized Christian (a "catechumen": a beginner who is being taught the principles of Christianity; a neophyte). Augustine encounters a number of important figures during this period of relentless searching, including Ambrose (the Bishop of Milan, who will eventually baptize Augustine) and Faustus, a Manichee luminary. He also encounters the profound doubt of the skeptical school and comes close to total skepticism in his own philosophy.
[V.1-13] Augustine begins by reminding us that everything and everyone is part of the whole of God's creation. This is in line with the Neoplatonic ideas discussed in Book III; nothing is inherently evil, and even the most "wicked" people continually praise God (though they do not know it). "You [God] see them and pierce their shadowy existence," he writes, and "even with them everything is beautiful, though they are vile." (Later, in his City of God, Augustine will liken such apparently evil people and things to the dark areas in a beautiful painting).
At age twenty-nine, still in Carthage, Augustine gets to meet Faustus, a respected sage of the Manichees. Before describing the encounter, Augustine takes the opportunity to make some points about the difference between scientific astronomy and the Manichee account of the heavens, a comparison that he was considering at the time.
Though he now knows that science is worthless without praise to God (who made the scientists and even the numbers they use), at the time he was impressed by astronomy's reliability in accounting for heavenly movements. In contrast, the Manichee account (which included claims that the eclipses serve to "hide" heavenly battles) was starting to seem inaccurate.
Augustine is initially impressed by the modesty Faustus exhibits--the sage simply refuses to theorize about subjects he doesn't know intimately (astrology is an example). Interestingly, however, Faustus' rhetorical flashiness doesn't impress Augustine, who claims that by this time he had learned to value the content of speech over mere loquacity. The net result of the interview was disillusionment: Augustine departed with more doubts than ever about Manichee myths and pseudo-science.
[V.14-21] Finding his students too rowdy and altogether too reminiscent of himself when he was a student, Augustine departed Carthage for Rome. Monica, who had accompanied him to Carthage, grieved at his departure, and Augustine confesses that he told her a white lie in order to get on the boat to Rome without delay.