 The opening of the Timaeus, depicting it as a sequel to a conversation about the ideal city-state that resembles the kallipolis of the Republic in important points, connects the project announced in the Timaeus to the Republic. This opening also presents the Critias as a sequel to the Timaeus. And Socrates’ request in the Phaedo to provide teleological causes for the explanation of the world, instead of the material causes employed in the cosmologies of the Presocratics (97b-99b), is answered by Timaeus’ account of the rational cause of the universe (the Timaeus, however, points out that the material causes of the Phaedo also have to be considered in order to explain the perceptible world). 