Glenn Gould would have turned 81 on September 25 if he were still alive. iTunes Essentials celebrates this date and features Glenn Gould’s Bach Goldberg Variations this week! Gould’s initial recording of the piece, from 1955, was an achievement of technical brilliance that established his career; his thoughtful return to it in 1981 illustrated how the same composition, played by the same musician, can become a wholly different work of art.