Mysticism is about existential ecstasy - an experience of heightening one's 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. Through a discussion of the lives of famous mystics, like Julian of Norwich and Jesus Christ, Critchley reveals how embracing the spectrum of mystical experience can refresh our thinking and help us live deeper and freer lives. Philosophical and playful, analytical and inventive, On Mysticism is a definitive account of humanity's quest to understand the divine, and a call to thinkers everywhere to broaden our minds to life larger than our selves.