I got to explain the four cardinal virtues today - prudence (practical wisdom), justice, fortitude (courage) and temperance (moderation). In our text Josef Pieper (expounding Thomas Aquinas, who's following Aristotle), argued you couldn't have any of the cardinal virtues without having them all - but also (with Aquinas going beyond Aristotle) asserted that you need to receive the theological virtues (faith, hope and charity/love) to really have the cardinal virtues.
I'd forgotten how I love this material - it's my first time teaching it in five years. By golly, I find I actually think it's true. (You can even be a religious naturalist about the theological virtues, I think, at least up to a point: you can't make yourself have hope or faith or love, but they evidently happen. Something makes them possible, something mysterious, bigger than us but of which we are a part.)