Most of 1981’s Tattoo You was conjured from a hodgepodge of unfinished tracks stretching back as far as 1973’s Goats Head Soup—as inauspicious a backstory as the band had in their catalog. Keith Richards said they just needed to jam something out before going on tour, an enterprise that by the end of the decade had swallowed their life as a studio band anyway. Others said Jagger and Richard weren’t getting along. Whatever the case, the end product was an album that didn’t just feel deceptively unified, but served as both a summary and a celebration of basically everything they’d done during a period where nobody seemed to know exactly what they were doing. “Start Me Up” started life as a reggae song for 1978’s Some Girls, “Waiting On a Friend”—an island-ish country ballad iced out with a solo by the jazz legend Sonny Rollins—for Goats Head Soup, and “Slave” was an R&B vamp for 1976’s Black and Blue. Jagger’s lyrics—mostly written and recorded in 1980—lent thematic consistency: He buckled for young girls (“Start Me Up”), complained about the weirdos next door (“Neighbours”), and discovered one could have a rich interpersonal relationship without music or sex (“Waiting On a Friend”). He was cresting 40, and as intoxicatingly arrogant in middle age as he’d been in youth. The band, once confined to verses and choruses, were increasingly stewards of a groove more important than any song. And with a few more trips around the sun under their belt, they sounded as entitled to their funk as they once were to their sprawl. A lot had changed, but with Tattoo You—lean, confident, world-weary but fired up—the band once again became The Rolling Stones.