THE GLENN GOULD LEGACY VOL. I: J. S. BACH. Glenn Gould, piano; Academic Symphony Orchestra of Leningrad conducted by Vladislav Slovak. CBS Masterworks 38614 (four records) (mono/stereo). As an introduction to the late Canadian pianist, this reissue set, mostly drawn from the CBS catalogue, could scarcely be bettered. Gould fanatics will want it, too, for the first release of the D-minor Concerto recorded live in Leningrad in 1957, an expressively freer reading than the contemporaneous studio version. Included, too, are the pianist's controversial, revelatory 1955 traversal of the "Goldberg" Variations, assorted suites, fugues and inventions, as well as an infuriating interview with Gould on why he abandoned concertizing and why Petula Clark is greater than the Beatles. The recordings span 21 years, so the sound varies, but Gould's ornery brilliance shines through everywhere.