Big dreams are rare but highly memorable dream experiences that make a strong and lasting impact on the dreamer's waking awareness. Such dreams can include vivid imagery, intense emotions, fantastic characters, bizarre elements of form and content, and an uncanny sense of being connected to forces beyond one's ordinary dreaming mind. These types of dreams have played significant roles in religious and cultural history, and even today people still experience them and find them intriguing and thought-provoking. Because of their infrequent occurrence and fantastical tendencies, however, big dreams have rarely been studied in light of modern science. While we know a great deal about the religious manifestations of big dreams through history and around the world, we have not yet integrated that cross-cultural knowledge with new scientific research on their psychological roots in the brain-mind system. In this volume, Kelly Bulkeley provides the first full-scale cognitive scientific analysis of highly memorable dreams, with an original theory about their formation, function, and meaning. He draws upon evidence from religious studies, psychology, anthropology, evolutionary biology, and neuroscience to build a very specific argument: big dreams are a primal wellspring of religious experience. They represent an innate, neurologically hard-wired capacity of our species that regularly provokes greater self-awareness, creativity, and insight into the existential challenges and spiritual potentials of human life.