"Gimme Shelter" is the Rolling Stones song most apt to be called apocalyptic, and was, aside perhaps from "You Can't Always Get What You Want," the best track on their 1969 album Let It Bleed. The most striking feature of the cut makes itself known right away: the shaky, shimmering guitar leads, whose catchiness nonetheless is imbued with a feeling of impending doom. The eerie, high, wordless vocals and dramatic piano that preface the verse add to the feeling that something dreadful is approaching just over the horizon. The verses are rather ordinary and workmanlike in comparison to the chorus, another great catchy Stones chorus that can be half-shouted and half-sung along with. The words, as in many Jagger/Richards songs, are ambivalent and ambiguous, not to mention sometimes difficult to understand even literally. The group might be seeking shelter from an oncoming disaster, or they might be seeking shelter in the escape offered by someone's love, or they might be seeking both. Sex and death: they can be strong bedfellows, and that's the coupling conveyed by "Gimme Shelter," even if that coupling is more implied by the mood than definitely spelled out by the words. To further establish the sense of uneasy tension that pervades the song, the Stones took the unusual step of having some of the backup vocals, and even some of the lead vocals, sung by African-American session singer Merry Clayton, who was able to reach full, high notes that Mick Jagger could not have. "Gimme Shelter" is sometimes assumed to have been written by the band about their disastrous free concert at Altamont in December 1969, but that wasn't the case. Let It Bleed was released that very month, as it happens, but of course "Gimme Shelter" had been written and recorded sometime before that. Some pundits have mused that "Gimme Shelter" presciently foresaw the demise of the 1960s and all that decade stood for, but if it foresaw any catastrophe, one could say that was Altamont itself.