Things that appear to be the same are sometimes quite different in important ways. When judicial activists appeal to the rule of law, for example, they may use exactly the same language as originalists, but their meaning is very different. Discussions of mysticism tend to be like that.
The history of Christian mysticism displays a tension between two impulses that are fundamentally incompatible with each other. Both impulses tend to express themselves in similar language, but what they mean by that language is quite different. Let me briefly describe each of these impulses.
Impulse One: Dionysian Neo-Platonism
A mystical author of the fifth or sixth century adopted the pen name of Dionysius the Areopagite. Known to scholars as “pseudo-Dionysius,” he wrote such works as The Divine Names and The Mystical Theology. Pseudo-Dionysius appears to have imbibed rather heavily of the Platonistic streams that had been flowing into Christian thought since the incursion of Gnosticism during the second century. There is sufficient ambiguity in his writing that we have to be careful in the charges that we bring against him, but he seems to have subordinated certain aspects of Christianity to neo-Platonism. Read more about The Christian Mystical Tradition(s)