John Zizioulas, metropolitan of Pergamon, is one of the most significant theologians of the late twentieth and early twenty-first centuries. He is well known not only to Orthodox Christians but also more widely through the publication of his books in several Western languages and, more importantly, his engagement with fundamental theological and philosophical themes that transcend confessional boundaries. He is a thinker, however, who frames his thoughts in essays and articles rather than in monographs. His most influential books, Being as Communion (1985) and Communion and Otherness (2006) are indeed collections of articles united by a common theme.