 Nicholas of Cusa’s most complete set of proposals about what is real occurs in his best-known work of 1440, De docta ignorantia: On Learned Ignorance. Here Cusanus addresses the four categorical realities traditionally found in Christian thought: God, the natural universe, Christ and human beings. On Learned Ignorance devotes its first book to God, the second to the universe and a third to the God-man, Jesus Christ. While its order mirrors the outflow from God and return to him, this book does not distinguish philosophy and theology as contemporary thinkers might, but unites them in a single overview of Neoplatonic Christian reality.