The most improbably exhilarating record I've ever heard was recorded 40 years ago, at a special late show in the Cologne Opera House, in front of a youthful capacity crowd. It's likely the only opera-related album I've ever listened to more than once, but that's fitting, since few of the 1,400 young Germans in attendance on January 24, 1975 were regulars, either. They'd come that night to hear something even rarer and less commercial: an hour-long improvisation on solo piano by a 29-year-old Pennsylvanian named Keith Jarrett.
Perhaps you think that 60 minutes of unbroken, off-the-cuff doodling sounds indulgent and esoteric, in which case you've never heard The Köln Concert, the double-LP of the show released later that year. Perhaps you think that an entirely improvised live jazz album by a single musician must have been, at best, a cult object, in which case it might surprise you to learn that it turned Jarrett into one of the least likely pop stars in history; to date, it has sold an estimated 3.5 million copies, placing it alongside Miles Davis's Kind of Blue as one of the most popular jazz records ever. By decade's end, Jarrett would be release a 10-LP (!!!!) live album and perform solo on Saturday Night Live. In the words of Guardian jazz critic John Fordham, "His concerts began to resemble religious rituals, attended by flocks of devotees for whom his music had a meditative, spiritual, and transformative power." The mid-'70s were a wild time.