Dionysius the Areopogite, writing in the fifth century of the Christian era, was perhaps the single most influential figure in the development of Christian mysticism in both the Eastern and the Western traditions. As David Henderson outlines at the beginning of this important and comprehensive review of the work of Dionysius and its influence up to and including its appropriation by Jung, the Areopogite fundamentally shaped the work of later writers and mystics including Eriugena, Thomas Aquinas, the author of The Cloud of Unknowing, Maximus the Confessor, John of the Cross,