Revision with unchanged content. Mystical experiences are altered states of consciousness in which the usual sense of the self dissolves. Research by neuroscientists has begun to clarify what happens in the human brain during mystical experiences. Does this research show that mystical experiences are all in the brain, and that they are not sources of knowledge about a transcendent reality? Might mystical experiences be valuable in other ways, even if they do not give us insight into a transcendent reality? This book is addressed to reseacrhers in the philosophy and psychology of religion.