This book collects 12 previously untranslated lectures by Castoriadis from 1982 to 1983. Castoriadis focuses on the interconnection between philosophy and democracy and the way both emerge within a self-critical imaginary already in development in the work of early Greek poets and Presocratic philosophers. Displaying both mastery of the relevant scholarship and original interpretation, he reveals the birth of a society that would place its highest value in calling itself and its institutions into question. He argues that this spirit would develop directly into the twin signatures of the Greek world, namely radical philosophy, on the one hand, and radical democratic practices, on the other. Like no previous interpreter, Castoriadis allows us to feel the existential need, already present in the earliest Greek thinkers, to question the significance of human existence and to share in shaping its meaning. The Greeks not only did this, he argues, they also began the equally important work of establishing the institutions to support such a project.