Dionysius the Areopagite and Theologia Mystica
The Syrian monk who adopted the name Dionysius and lived around the year 500 AD originated in the church of the East but has been one of the greatest influences on the mystical life of the church in the West. His negative theology or way of unknowing articulated the classical apophatic spirituality adopted by later writers such as Meister Eckhart, the author of The Cloud of Unknowing and St John of the Cross.