Deny’s spiritual exercise took the form of a dialectical process, consisting of three phases. First we must affirm what God is: God is a rock; God is One; God is good; God exists. But when we listen carefully to ourselves, we fall silent, felled by the weight of absurdity in such God talk. In the second phase, we deny each one of these attributes. But the “way of denial” is just as inaccurate as the “way of affirmation.” Because we do not know what God is, we cannot know what God is not, so we must then deny the denials: God is therefore not placeless, mindless, lifeless, or nonexistent. In the course of this exercise, we learn that God transcends the capability of human speech and “is beyond every assertion” and “beyond every denial.” It is as inaccurate to say that God is “darkeness” as to say that God is “light;” to say that God “exists” as to say that God does “not exist,” because what we call God falls “neither within the predicate of existence or non-existence.” But what can this mean? The exercise leads us to apophasis, the breakdown of speech, which cracks and disintegrates before the absolute unknowability of what we call God.
— Karen Armstrong in her book, The Case for God, writing about Denys the Areopagite.