The Spectrum of Consciousness by Ken Wilber (1973). I’ve read an awfully lot by Ken Wilber, and it wasn’t easy to pick a favorite, so I went with his first book (Spectrum) rather than his magnum opus, the very large tome Sex, Ecology & Sprituality. Given that Wilber is nothing if not comprehensive, SES might have gotten the nod, but in Spectrum I encountered for the first time someone who had read just about everything that I would every want to read (and still haven’t) and who then makes some sense of it all. Although Wilber has refined and revised his perspectives , you get a sense of his youthful exuberance in writing this book. Wilber reports that he was a (typical?) Duke undergrad when he was struck by a “what’s the meaning of all this?” moment and went off in search of answers. While earning an ABD in biochemistry he ranged over thought from East and West to make some sense of it all, and this book represents his first draft. It’s really quite amazing, and it’s kept me following his work for about three decades now.