Reading Heinrich Cornelius Agrippa’s encyclopedic study of magic is like stumbling into a vast cabinet of curiosities, where toad bones boil water, witches transmit misery through optical darts, and numbers, arranged correctly, can harness the planets’ powers. Anthony Grafton explores the Renaissance polymath’s occult insights into the structure of the universe, discovering a path that leads both upward and downward: up toward complete knowledge of God, and down into every order of being on earth.