What set Syd Barrett off on his madness, whether it was LSD, natural brain chemicals or the strobe lights at the rock concert (one interesting theory bruited about)—whether Barrett's absence triggered Pink Floyd's most plaintive moments—"Wish You Were Here," "Shine on, You Crazy Diamond," the slashing bitterness of The Wall and maybe the cold morbidity in my favorite non-Barrett Floyd song, "Free Four," in which the Yanks bear their part for unhinging poor Syd ("All aboard for the American tour!")—whether it was that ambient R.D. Laing strain running loose in the day that confused Barrett's longtime, not momentary, lapses of reason with genius—whether he was the laughing madcap or the lunatic in the grass—whatever or whomever Syd Barrett was, his and Pink Floyd's No. 6 in the U.K. single "See Emily Play" is still an epochal moment of 1960s pop.

"See Emily Play" is so frighteningly bizarre, so soulful and so painful that even the likes of David Bowie could only trace around its outline when he covered the tune for his album Pin Ups. I didn't hear the original until years after hearing the Bowie version, and it was like seeing the difference between King Kong and a chimp. The song is still unnerving. The screaming guitar solo that's like an F-16 crashing into the studio; the slamming stop of the wah-wah pedal; the racing rinkity-tinkity piano speeding up like a nutter's thoughts, spiraling into incoherence. This little 45 of Pink Floyd's was the true egg of psychedelic music, and everyone from the Beatles to the Jefferson Airplane just chased the chickens around.

Barrett died July 7. Though bedeviled with stomach troubles and diabetes, Barrett spent the last 20 years peacefully gardening and avoiding the public. Wikipedia claims that Barrett got to see a BBC special on Pink Floyd, and that while the concert footage seemed noisy, "See Emily Play" certainly sounded good after all those years.