[This post covers on chapter that has been split over three days in the reading schedule.]
Augustine returns to the question of miracles, and asks why there are no more to confirm our faith. He points out that even if miracles continued, there will always be those who remain willfully skeptical.
And yet, it's not really fair to say that there are no miracles. There have been plenty which have confirmed Christ's ascension into heaven--though since the closing of the canon, they have been rare, small, provincial, and largely reported by Christians (and so somewhat untrustworthy--"too unauthoritative to be received without some difficulty or doubt"). The rare big miracle does happen, but again they can not be turned to for absolute demonstrations in the same way that the miracles of Scripture can.
Augustine then proceeds to give several examples of miracles both big and small. Some involve healing, some involve conversion, and some are tied to the relics of the saints. Augustine will have more to say on this last in the next section (lest we think he's encouraging the idolatry of worshiping the martyrs).