A stolidly thorough documentation of conductor Arturo Toscanini's long career--with hardly a single downbeat left unrecorded from the 19-year-old cellist's surprise conducting debut in Rio de Janeiro (Aida, 1886) to the octogenarian's remarkable feats of endurance with the NBC Symphony. In between are the stints with La Scala, the Met, the N.Y. Philharmonic, Bayreuth, and other opera houses and orchestras. Not that Sachs fails to emphasize the motifs running through this marathon concert. Toscanini's opera-house reforms receive the appropriate attention, as does his campaign to de-encrust opera scores from the turn-of-the-century additions and distortions of strong-willed singers: ""the artist must be persuaded or forced to conform to [the conductor's] vision of the opera,"" a philosophy most totally brought to actuality at La Scala in 1920. As for the legendary temper, Sachs believes that this was ""not at all native to his personality"" but rather the spur needed ""to upset the lethargy"" of lazy traditions. Also duly described, in more detail than ever before: the hot-and-cold relationships with Puccini, Debussy, R. Strauss, and others; the anti-Fascist politics that got Toscanini into trouble at home but added to his American adulation; and the guilt-ridden philandering that continued into his seventies (""He could not forgive himself but neither could he control himself in the sexual-amorous aspect of his life""). A truly complete biography, then--far more so than George Marek's breezy 1975 portrait. Unfortunately, however, Sachs has found no shape or thrust for his research, writes intelligently but without zest or humor, and has drawn no real personality out of the masses of detail and quotations. So, with all its pop-cultural faults, Marek's remains the layman's Toscanini biography--this one is for scholars only.