In May 1953, under the supervision of the psychiatrist Humphry Osmond, Huxley took four tenths of a gram of mescaline in his Los Angeles home and spent the following hours recording what he experienced, work he published the next year as The Doors of Perception. His central claim was that ordinary consciousness works as a reducing valve, filtering an otherwise overwhelming flood of reality down to what an organism needs to survive, and that mescaline, like the practices of contemplatives before it, could loosen the valve and let more through, an experience Huxley described in terms strikingly close to the unitive mysticism of Vedanta and Christian contemplatives. A second essay, Heaven and Hell, followed in 1956, extending the argument to art, visionary experience and the darker states a loosened valve could also open. Huxley described a real and, to him, philosophically serious experience; he did not present a discipline or a method to be followed, and this atlas describes his claims and their influence rather than treating either essay as instruction.
That influence was large regardless: both essays fed directly into the language and expectations of the 1960s counterculture, gave later writers on psychedelics a framework to work from, and, on Huxley's own final afternoon in November 1963, LSD administered at his written request was the last thing he took before he died of laryngeal cancer, on the same day John F. Kennedy was assassinated.