The Timaeus-Critias is a Platonic treatise in two parts. A response to an account of an ideal state told by Socrates, it begins with Timaeus' theoretical exposition of the cosmos and his story describing the creation of the universe, from its very beginning to the coming into being of man. Timaeus introduces the idea of a creator God and expounds the structure and composition of the physical world. The Critias, the second part of Plato's work, comprises an account of the rise and fall of Atlantis, an ancient, mighty and prosperous empire ruled by the descendents of Poseidon, which ultimately sank into the sea. A key Platonic text, the Timaeus-Critias formed a central basis to Western thought and influenced subsequent philosophical doctrine. In his introduction, Thomas Johansen discusses how the Timaeus-Critias relates to Plato's work and ancient thought, and explores the main themes of the dialogue. This edition includes explanatory illustrations, a summary of Timeaus' contents and notes on the text.