This book includes five public lectures given by Professor Ioannis Zizioulas (currently Metropolitan of Pergamum and Academic) at the Goulandris-Horn Foundation in 1983, which systematically move towards the hermeneutic investigation of the encounter between Hellenism and Christianity, while as an Epimeter follow three other short studies that mainly deal with with the importance of this meeting for the present and the future of Hellenism and Orthodoxy in the modern world.