Donna M. Altimari Adler, Ph.D., long time member of the International Society for Neoplatonic Studies, is pleased to announce that Brill Academic Publishers will be releasing her new book, Plato’s Timaeus and the Missing Fourth Guest: Finding the Harmony of the Spheres on December 24, 2019. This technical work in ancient philosophy solves a very old puzzle and will be most useful to scholars of ancient cosmology, the history of ideas, and the roots of western music theory.