Le Monde de la Politique is a commentary of Plato's atlantis story (Timaeus, 17-27 and Critias). Its aim is to show the importance of this story in Plato's political thought. Pradeau's study insists on three aspects of Critias story: its ambigious status of a fiction which says something true about the Socrates's city (conceived in the Republic), its relation to the historical writings (Pradeau shows that the material of archaic Athens and Atlantis descriptions is almost entirely borrowed from Herodotus,II) and its belonging to a periphuseos research. After having described the nature of the world and of the human being in the Timaeus, Plato gives an account of a third kind of living being, the city. Le monde de la cité gives an explanation of this 'political physiology'.