The Mysterious Universe is a science book by the British astrophysicist Sir James Jeans. It is an expanded version of the Rede Lecture delivered at the University of Cambridge in 1930, and begins with a full-page citation of the famous passage in Plato’s Republic, Book VII, laying out the allegory of the cave. It makes frequent reference to the quantum theory of radiation, begun by Max Planck in 1900, to Einstein’s general relativity, and to the new theories of quantum mechanics of Heisenberg and Schrödinger, of whose philosophical perplexities the author seemed well aware. This New Revised Edition was first published in 1932. A popular book to this day, and a valuable addition to any reader’s science book collection.