Mysticism is about existential ecstasy – an experience of heightening ones senses and self into a sheer feeling of aliveness. Mystical experiences offer us a practical way to open our thoughts and deepen the sense of our lives, whether through a mainstream connection to God or by taking part in mind-altering experiences. Here, Simon Critchley explores the history and practice of mysticism, from its origins in Eastern and Western religion, through its association with esoteric and occult knowledge, and up to the ecstatic modernism of T.S. Eliot and others.