When the fruits of the glimpse are seemingly withdrawn--and especially so when this happens if the glimpse has been brought on by the work of meditation--a deadness will seem to close in on the feeling and a dullness on the mind. If this condition goes deep enough, it becomes depressive and is more or less what the saints have called the Dark Night of the Soul. This is not permanent. The seeker should not despair, but his patience will be stretched and he must accept its happening. If he sees no cause for which he is to blame, then the acceptance becomes an act of faith and it will not be in vain.
-- Notebooks Category 23: Advanced Contemplation > Chapter 3: The Dark Night of The Soul > # 12