This looks like a good link. I haven't read it yet...
"...There is a deeper reason for a mystic being "mute" — that is what the name imports — than that he wishes to make a mystery of his discoveries. He is "mute" because, as a mystic, he has nothing to say. When he sinks within himself he finds feelings, not conceptions; his is an emotional, not a conceptional, religion; and feelings, emotions, though not inaudible, are not articulate. As a mystic, he has no conceptional language in which to express what he feels..."
The distinction between mysticism of this type and evangelical Christianity, from the point of view which is now occupying our attention, is nevertheless clear. Evangelical Christianity interprets all religious experience by the normative revelation of God recorded for us in the Holy Scriptures, and guides, directs, and corrects it from these Scriptures, and thus molds it into harmony with what God in His revealed Word lays down as the normal Christian life.
The mystic, on the other hand, tends to substitute his religious experience for the objective revelation of God recorded in the written Word, as the source from which he derives his knowledge of God, or at least to subordinate the expressly revealed Word as the less direct and convincing source of knowledge of God to his own religious experience. The result is that the external revelation is relatively depressed in value, if not totally set aside
Interesting how many feel they need "mysticism" in their Christian walk.