21st Century Schizoid Man

Sinfield's lyric is a series of disconnected images that criticise the Vietnam War, with "death seed" referring, he said, to Agent Orange. He wanted the words to sound violent and aggressive, and he found the title leaning against a mantelpiece. The introduction is a sound McDonald made by pressing his forearm on the keys of the studio's reed organ until it malfunctioned and wheezed. The main riff is played in unison by McDonald on alto saxophone and Fripp on overdriven guitar over Lake's bass, and Lake wrote its first six notes and McDonald added the last three. The Mirrors section that follows runs in 6/8 and includes Three Score and Four, which McDonald wrote in his army band days.

Fripp recorded his dissonant guitar solo as an overdub on 4 August 1969, picking down and up in alternation. Guitar World ranked it number 82 in its 2008 list of the top 100 guitar solos. McDonald recorded his alto solo crouching, to add angst. Giles said he suggested ways to link the sections, such as the speed-up into the six-four riff, and that he borrowed from something by Duke Ellington for the second ending. The backing was done in one live take.

Reception and legacy

Melody Maker called it "brutally exciting" in 1969. Pitchfork put it at number 104 on its 2006 list of the 200 greatest songs of the 1960s, where Joe Tangari called it a "seven-minute hellstorm of gonzo guitar, shifting meters, and nasty sax". Fripp calls it the first heavy metal song. King Crimson opened their Hyde Park set with it on 5 July 1969, and it was the encore on the 1972 British tour, the one familiar point in a set of new material. Ozzy Osbourne, Entombed and Voivod have recorded versions, Bad Religion's 1990 song 21st Century (Digital Boy) pays homage, and Kanye West sampled it on Power.