I found there was something extremely "Zen-like" in Thomas Moore's book, Dark Night of the Soul (USA) in the way he is very reassuring as he describes the experiences of the blackness in life that appears from time to time. He indicates that a sufferer is not alone in times of despair, despite feelings to the contrary - we all have our "Dark Nights". The experience of a Dark Night is not there to be understood in an intellectual, superficial way as this would make the entire experience very un-transformative. The Dark Night is there to assist our souls to grow and develop.