|With friends in Bangkok|
The word "mystic" derives from the Greek word muein which means "to close," in this case, to close one's mouth (e.g., see here, p. 6). One keeps one's mouth closed because of a felt God-encounter that cannot be expressed, hence a non-discursive experience (one cannot "discourse" about it).
This makes sense of classic texts as The Cloud of Unknowing and The Dark Night of the Soul. These works speak of a "dark knowledge" that is "dark" precisely because the 5 senses shed no light on the experience. Via our 5 senses we cannot know God as we can when these senses are "darkened." Thus the "dark night of the soul" does not essentially refer to something like "going through a really hard time in life," but instead refers to finding God non-discursively (i.e., I cannot adequately discourse about it). Going through a really hard time can issue forth in dark knowledge, but dark knowledge is not to be equated with the difficult time.
I find this sensible since the God I believe in transcends human sensibilities and rationality. God cannot be fully captured in my experience and by my reason. It is at this point that, if one speaks at all, one resorts to poetic-figurative-fictive discourse which, by the way, is not equivalent to "untruth." (My doctoral dissertation dealt with this; viz., issues of "literal" vs. "figurative" language and their referential capacities. See also French philosopher Paul Ricoeur's work on interpretation theory and a "surplus of meaning.")