Christian thinkers have divided virtue into seven categories: four Cardinal virtues—which all civilized people recognize—and three Theological virtues—which, as a rule, only Christians know about.

In this video, which illustrates a section of Mere Christianity, Lewis looks at the four Cardinal virtues: prudence, temperance, justice, and fortitude. The word ‘cardinal’ has nothing to do with ‘Cardinals’ in the Roman Church, Lewis notes. Rather, es from a Latin word meaning ‘the hinge of a door’. These were called “cardinal” virtues because they are “pivotal.”