After the assassination Julius Caesar, Cicero wrote “On Obligations” to his son Marcus, who was studying in Athens. He obviously meant it for the public as well, but it has the sense of a father writing to a son.
For Cicero, our obligation to aim for the best good among goods guides our moral life. All these goods stem from the four cardinal virtues: prudence or wisdom, justice, courage, and temperance (or self-control).
In other words, he names the kind of virtues that are universally accessible to people—the so-called civic virtues. Christians recognize these virtues as part of God’s common grace. They are not works of condign merit before God, but simply allow society to work.
They contrast the theological virtues which only grace can bestow, namely, faith, hope, and love. Yet the cardinal virtues are still naturally good. And Christians can perfect them by infusing the whole trail of virtues with love.
So prudence in love changes the whole scope of the cardinal virtues in ways that show the transcendent glory of God. Anyone can make a wise decision among alternatives, but we know the end of our wisdom is love or Love, which is God.
That means it may be wise to choose an aim for love’s sake that the physical man (in contrast to Paul’s spiritual man) cannot discern apart from the Spirit which makes one spiritual.