A Gertrude Stein-ish society spinster ""thought it would be wonderful to give music to the farmers"" around her Berkshire Mountains country retreat, and, forty years later, Tanglewood rivals Salzburg and Bayreuth as the summer music festival and finds its historian in Herbert Kupferberg. No shortage of illustrious names in the cast, but all defer to Serge Koussevitzsky, the single-minded emigre conductor of the Boston Symphony who parlayed the concert-in-a-tent pleasantry into a self-reflecting, Saarinen-designed, conservatory for incubating talent--especially ""Koussy"" proteges. Koussevitzsky's eloquently mangled English (""Study as more as you can""), his feuds, and his discoveries (Leonard Bernstein, Lukas Foss, Dorothy Maynor, Sarah Caldwell) dominate the landscape, and when successors Munch and Leinsdorf enter, excitement exits. Kupferberg steers just to one side of press-agentry, serving up some of the bad notices along with the raves, allowing personality clashes and student tensions to surface, but always returning to head-counting to reaffirm the triumph. Best moments: an interview with Bernstein that lingers on convert Koussevitzsky's ""Jewishness""; making the rounds of simultaneous music-making on a typical Tanglewood day; Boris Goldovsky's recollection of an unteachable Mario Lanza. Kupferberg's intimacy with the orchestral milieu (""The quickest way to a musician's heart is through a canceled rehearsal"") and a splendid display of see-them-when-they-were-young photos will move this volume out of the pedestrian lane and into a lot of music-lovers' homes come Christmas.