The present study examines the significance of the mythical for Plato's philosophy and for classical thought after him. It concentrates on the closing myth of the Politeia and the commentary on this text by the Neo-Platonist Proclus. From this basis, it is possible for the author to make general statements on the function and status of the mythical in philosophy. In contrast to the treatment in comparable publications, the myth is not isolated historically nor as an element in the dialogue. Thus it is possible to reflect in a new way on its relationship to philosophical thought in Classical Antiquity; the 'rationality' of the mythical arises from the reformulation of the dialogue connected with it.