St Symeon was the most important teacher of mystical experience of God in the Orthodox Church. This book seeks to place the teaching of the discourses in their proper context, both among Symeon's other writings and with regard to his sources in the Tradition. Included is a sketch of Symeon's life and times, together with an extensive discussion of this thought, particularly against its background in the ascetical, mystical and theological literature of the Christian East prior to the 10th century.