The image of a skull in Christian art can symbolize many things, but it’s largely a reminder of our mortality, Christ’s victory over death, and that this world is not our permanent home (Heb. 13:14). Some find these images unsettling, and that’s the idea: they are meant to disturb and upset—but in a good way. The Latin term for this reminder is memento mori—”Remember, you must die.”
As the Catechism reminds us, “Death is the end of earthly life . . . remembering our mortality helps us realize that we have only a limited time in which to bring our lives to fulfillment” (CCC 1007). Many of the saints (e.g., St. Jerome, St. Gerard, St. Francis) used images of skulls and other memento mori objects for spiritual contemplation: to prepare for the hour of death, to recognize that time on this planet is very short and that the battle against sin is great, and that one day we will all stand before Christ’s tribunal to render an account of our own deeds (CCC 1059).
Like the saints, these memento mori reminders should compel us to a deeper contemplation of our mortality in preparation for the hour of death, for no man knows the hour when Christ will come for us. A healthy contemplation of our death and the judgment that follows is good medicine for the soul.
The Church encourages us to prepare ourselves for the hour of death. Every action of yours, every thought should be those of one who expects to die before the day is out. Death would have no great terrors for you if you had a quiet conscience. . . . Then why not keep clear of sin instead of running away from death? If you aren’t fit to face death today, it’s very unlikely you will be tomorrow (CCC 1014).