Oh... i was mistaken. "void of emotions" has nothing to with crisis of faith hahahaha. I'm actually not gonna even bother with this one. Carry on! Oh, and linda, you apparently missed my last sentence in the post but i guess you didn't care at all so you were in a hurry to tell me that before actually reaching the end, cute. :)
Well, you were partly right, anyhow. It is an old idea.
I think what Mother Theresa describes in the link from linda is like the Buddhist dukka (dukkha?) nanas - the "suffering" phases on the path to enlightenment. Where the mystical is suddenly absent and one is left destitute and bereft of that former comfort and has to almost relearn the mystical connection without aid of that connection. It is the death of self which must be experienced after the initial enlightenment and before which a true acquiescence to the metaphysical can begin. (if I'm interpreting correctly, here)
I found a copy of Mysticism by Evelyn Underhill online and read the first 12 chapters of Part II. I think she was a Catholic mystic. At any rate, her description is that it is like a spiritual fatigue - which I understand (I think). She covers the St. John poem in that book very nicely.