Professor Olaf Ziggon, one of the greatest contemporary researchers and experts in ancient philosophy, offers the reader something that they will vainly seek in the known manuals: he brings ancient philosophy to life from within, showing how it understood itself and its role in society, reconstructing the portrait of the ancient philosopher and tracing the roots of his claim to know the world and humanity through Reason. From this fruitful perspective, the fundamental problems of ancient philosophy can be understood in their internal unity, that is, as multiple answers to permanent and constantly recurring questions. Cosmology, physics, politics, and ethics are presented in a vivid and generally accessible way to their common denominators, which remain alive and relevant for us.