At five years old, Thomas Aquinas is said to have posed to his catechism teacher the question of all questions: “But master, what is God?” The Creed gives us a succinct but inexhaustible answer. The one God, unlike any other being in the cosmos, is fully actual and unconditioned. Furthermore, God is Father: he generates, cherishes, and directs all things. And God is Creator—the noncontingent source of all contingent reality.