This is perhaps the greatest test of all, this phase of the aspirant's career which has been called "the dark night of the soul." Any one or all of several different causes may bring it on, any one or all of several different results may ensue. In that terrible darkness he will find himself absolutely alone, able to depend on nothing else than what he finds within his own innermost being. Without anyone to guide him and with none to companion him, he will have to learn an utter self-reliance if he is successfully to gain one of these results. It is useless to complain of the terror of this experience for, from the first moment that he gave his allegiance to this quest, he unconsciously invited its onset. It had to come even though the day of its coming was yet far off.
-- Notebooks Category 23: Advanced Contemplation > Chapter 3: The Dark Night of The Soul > # 70