Here, Augustine turns his philosophical guns to their highest setting, giving a full blast of what is best in life:
Augustine of course has a slightly more subtle approach: "By definition, our supreme end is that good which is sought for its own sake, and on account of which all other goods are sought... For the moment, we shall say that the ultimate good is not so much a good to end all goods as, rather, one by which goodness reaches its fullest consummation."
Evil is similar--it is that which is to be avoided as much as possible and in its heights (or depths) that which "reaches the very height of harm."
What we need to understand is the different perspectives on good and evil between the two cities. In a sense, this is the goal of everyone who claims to love wisdom. This can mean in the context of the soul, or of the body, or both (this is the division which Varro makes in his works). Augustine follows Varro's schemata as he works through the various options. This can include the pursuit of pleasure, peace ("serenity"), a combination of pleasure and peace, or simply meeting the basic needs of life (think Marx with this last one). What's more, we can look at these different options in different ways, through the means of virtue, pleasure, or a combination of both. (Which, if you're keeping track, now puts us at 12 possible combinations.) Added to this is the possibility of pursuing these things for the individual or for the society of the whole (which now brings us to 24 options). Finally, each of these options may be argued to be certain, or relative and uncertain (which means there are 48 philosophical possibilities). Beyond this, one may be Cynical about philosophy, or un-Cynical about philosophy (96 possibilities). Likewise one can pursue philosophy with action in mind, or contemplation, or a mixture (finally we're at 288 possibilities). Varro then narrows these options back down to the one school he thinks the best one, the Old Academy (the Platonism of Plato, rather than of Plato's followers).