For those who lived through what is sometimes called the Psychedelic Revolution, Terrence McKenna is a legend. Once referred to as "the intellectual's Timothy Leary." Terence attained iconic status as a radical philosopher, futurist, cultural critic, and raconteur. His unorthodox ideas about the evolutionary and cultural impact of psychedelic drugs shocked many and resonated with many others. In 1971, we embarked on an expedition to the Amazon, bent on uncovering the real mystery behind psychedelic experience. Terrence died in 2000, never to learn if his predictions about the end of the world, in his particular sense, were true. As Terence's younger brother and only sibling, I grew up with him in a small town in western Colorado during the fifties and sixties. Traveling together in the Colombian Amazon in 1971 with a few other kindred spirits we called our band "the Brotherhood of the Screaming Abyss." As Terence's brother, I helped him create and develop many of "his" ideas. Terence became the spokesman for the alien dimensions accessed through psychedelics, a philosopher of the unspeakable, a beloved and sometimes reviled bard of the marvels and occasional terrors waiting in the recesses of human consciousness. By choice and inclination, I stayed in the background, pursuing a scientific career in disciplines that ranges from ethnopharmachology and ethnobotany to neuroscience. Since Terence's death, we've witnessed the first decade of a new era that by all early indications will be as strange and disturbing, as full of hope and despair, as any period that humanity has yet endured. I've been drawn to look back at how our personal world began. I wanted to retrace the journey that took us from our childhood to our separate destinies, stopping to revisit the people and ideas that shaped us - from Amzon