Orthodox theology is intimately linked to spiritual experience:it has a very different meaning to the present usage of this word coming from academia. The scientific methods developed in the West since the seventeenth century can of of benefit in many regards, but without strong roots in the Orthodox tradition theology risks being "eaten up" by the human sciences. These roots are in the mystical tradition of the Church as passed down from the the beginning and expressed in the lives of saints, iconography etc. Thus this work has both a theoretical and a practical scope, of relevance to all Christians. AUTHOR: Dr Jean-Claude Larchet is one of the most notable living philosophers and authors on Orthodox Christian Patristics. He holds a Ph.D in philosophy from the University of Nancy and a Ph.D. in theology from the University of Strasbourg. A teacher of philosophy for nearly thirty-five years, he is an author of over thirty books and countless articles whose work has been translated into seventeen languages. His magnum opus, Therapy of Spiritual Illness, and several other works have been translated into English to wide acclaim.