This book has long been known as a classic in the study of human consciousness, having been praised by such luminaries as P. D. Ouspensky and the psychologist William James. The author puts forth and supports the idea that human consciousness is evolving and that we, as human-kind, are moving toward a much more enlightened state. People who have experienced such states and who have appeared at certain times to move humanity forward are covered in the book including such figures as Jesus, Mohammed, Francis Bacon, Socrates, Spinoza, Emerson, Thoreau and many more. Bucke also writes from first-hand experience, having had his consciousness briefly awakened at age 35. According to the author the evidence is clear-all people at some time in the future will have far more wisdom and intelligence than we do today.