Cornelius Castoriadis, a multidimensional and pivotal figure in the fields of philosophy, epistemology, psychoanalysis and political thought, is closely associated with the breaking down of established ways of thinking and acting and with the creation of new ways of instituting society.The notion of creation permeates his entire work, and on the basis of this notion a thought on art is developed, sometimes on theatre in particular, deriving from myth and from the major works of ancient Greek drama. The main argument of this essay is that this thought is crucial to the analysis and understanding of ancient Greek tragedy as a form of thought and action deeply interwoven with the concept of autonomous society. From this point of view, tragedy represents an institution of ancient Athenian society which affirms and activates the central imaginary signification of the polis.