 Like Schopenhauer, Søren Kierkegaard saw humor as based on incongruity and as philosophically significant. In his discussion of the “three spheres of existence,” (the three existential stages of life—the aesthetic, the ethical, and the religious), he discusses humor and its close relative, irony. Irony marks the boundary between the aesthetic and the ethical spheres, while humor marks the boundary between the ethical and religious spheres. “Humor is the last stage of existential awareness before faith” (1846 [1941], 448, 259). The person with a religious view of life is likely to cultivate humor, he says, and Christianity is the most humorous view of life in world history ([JP], Entries 1681–1682).