The aria is thirty-two bars of simplicity. Then thirty variations happen to it, everything that can be done to a theme is done, and when the aria returns at the end, note for note, you are the one who is different. Gould recorded it twice. At twenty-two he played it like a young man certain the world was his to dismantle. At fifty, a year before he died, he played it like someone putting each note carefully back where he found it. The same hands, the same keys, and between them an entire life.