In this comprehensive and well-grounded study, Birgitta Mark examines the idea of mysticism, exploring the evidence and possible explanations for mystical experiences, including the latest scientific theories of consciousness and neuronal activity. As a case-study she explores in-depth the writings and later scholarly interpretations of the mystical experiences of St John of the Cross, the 16th Century Spanish philosopher who sought to transcend mere physical existence through meditation and hardship . This well researched book will be of great interest to scholars of religion and psychology and others who wish to learn more about mystic states and the people who have sought to achieve them throughout history.