In 'Timaeus', Plato undertakes to give a thorough account of the world in which we live. For Plato, this means explanation in terms not just of physical laws, but also of metaphysical and religious principles which, he argues, are more exact than recalcitrant physical nature. Against this background, Plato provides a description of the world, based on the four elements, and in particular of the physical and psychological constitution of its human inhabitants, which is a tour de force and remained a paradigm of science for two thousand years. The mysterious preamble to Timaeus contains the first account in literature of Atlantis, while the fragmentary Critias, unfinished by its author, expounds the nature of the lost continent’s ideal society. Sir Desmond Lee’s translation admirably preserves the lucidity of the original Greek and his appendix on Atlantis should be read by anyone interested in this perennial myth.