Circumstances were inauspicious when pianist Keith Jarrett and ECM Records owner-producer Manfred Eicher rolled into Cologne, Germany, in January of 1975. Jarrett hadn’t slept the night before and was in pain. Worse, the Bösendorfer piano they’d requested had been replaced by an inferior model which, according to Jarrett, “sounded like a very poor imitation of a harpsichord or a piano with tacks in it.” Yet the hour-long solo concert he performed around midnight at the city’s opera house, wearing a brace and nearly falling asleep at his instrument, was a deeply entrancing meditation on rhythm, whose double-vinyl recording became both the best-selling solo jazz and solo piano albums in history. Jarrett’s extemporized fantasia drifts seamlessly from idea to idea, sometimes settling into a two-chord vamp for minutes at a time. More relaxed than most of his other solo recordings, it boasts a full complement of Jarrett’s whooping, sighing and foot-stomping affectations while still offering a ravishing introduction to the art of improvisation. Richard Gehr