For the great paradox of all theology, but particularly of mystical theology, is that we know God and we do not know God. While the theme of unknowing and ignorance flows through the mystics, we also find that they talk constantly about God as an intimate friend whom they know very well. Again, while mystical theology from Gregory of Nyssa to John of the Cross keeps harping on the theme of darkness, we suddenly realize that the darkness is light. How do we explain such paradox? How do we explain that at the same time we know God and do not know God?
— William Johnston, Mystical Theology