Few of us are straight arrows, maintaining a predictable arc throughout our lives. We veer off course, careening at times, before coming to rest at the end of our days. Pianist Glenn Gould's 1955 recording of Bach's Goldberg Variations was the hallmark of a young man, shot from a tightly-strung bow. Insanely fast tempos, wild energy. You could almost call it reckless. But his trajectory changed over the years. His 1981 re-recording of the piece bears little resemblance to the earlier one. We'll sample both recordings today, on what would have been Gould's 80th birthday.