By 1962 Watts had spent a decade explaining Zen and Taoism from the outside of any lineage; The Joyous Cosmology, published that year with an original foreword by the Harvard psychologists Timothy Leary and Richard Alpert, turned to a different outside vantage point, his own recorded experiences with LSD, psilocybin, mescaline, DMT and cannabis. He framed the book as the record of someone seeking understanding rather than sensation, reading the experiences through the same non-dual lens as his Zen and Vedanta writing: the felt boundary between a self and the world, he argued, is exactly the construction these substances can temporarily dissolve. It belongs to a real historical moment, alongside Aldous Huxley's mescaline writing and Leary and Alpert's own psilocybin research, and its honest limit is inseparable from its method: it is one already-sympathetic writer's memoir and argument, not a controlled account of what the drugs do to people in general.
Watts died in 1973 having reached a large readership but nothing like the audience he has now. Since the 2010s his KPFA-era broadcasts and later recorded lectures have found a second life on YouTube, podcasts and streaming platforms, and short clips of his voice are widely reused as spoken-word samples across ambient and electronic music, a use his own estate has had no practical way to control. The writer Jules Evans has suggested that few philosophers rival his reach on YouTube besides Jordan Peterson, his own impression rather than a measured count. None of this is evidence that the ideas being repeated are sound; a sentence's popularity as a sample is a fact about distribution, not about whether it is true, and the atlas keeps the two claims separate rather than letting the first stand in for the second.