What is a dream? Why do we dream? How do our bodies and minds use dreams? These questions are the starting point for this unprecedented, astonishing study of the role and significance of dreams, from the beginning of human history. An investigation on the grand scale, encompassing literature, anthropology, religion and science, it articulates the essential place dreams occupy in human culture, and how they functioned as the catalyst that compelled us to transform our earthly habitat into a human world.