New Yorker music critic Porter has been cutting back on his reviewing in recent years, sharing his column (ever more generously) with a colleague: the section devoted to the third season here, 1979-80, is half the length of the other two. So the musical '80s may not be as fortunate as the '70s--which have been chronicled, perhaps as no other decade has ever been, in the warm, detailed, exuberantly well-informed Porter manner. From A Musical Season ('72-'73) to Music of Three Seasons ('74-'77) to this new collection, the elegant tone remains consistent, the standards never waver, and the enthusiasm hardly wanes a bit--even if fussy exasperation does occasionally set in (""Oh, really! How can a clever man be so silly. . . ."") when Porter confronts yet another example of someone (usually an opera stage-director) disregarding the composer's intentions. The other Porter hallmarks are here too: his fearless pursuit of small points (the alternate versions of the trumpet calls--""dum-diddle-dum-dum"" vs. ""diddle-dum-dum-dum""--in Leonore No. 3); his adventurous trekking not just to Europe, but to opera companies and festivals around the US; his eloquent championing of such modern Britons as Michael Tippett and Peter Maxwell Davies; or his fierce concern with the elements surrounding music performance (an essay on radio-broadcast introductions). Opera, of course, remains his forte--instrumental performances appear, but not with enough consistency to provide real context--so there are small-scale, definitive discussions of a few Verdi operas (Don Carlo, Stiffelio, Ballo), along with intriguing rarities and world premieres (Musgrave's Mary, Queen of Scots, Menotti's La Loca, Penderecki's Paradise Lost, the complete Lulu). And, inevitably, there is the Metropolitan Opera (""the most backward of the world's big opera houses""), where the fair-minded Porter can find a superb John Dexter staging of Billy Budd as well as the John Dexter who should be sent ""to opera school to acquire some understanding of nineteenth-century opera and ways of staging it."" True, some of Porter's preoccupations begin to seem like blind spots in this second long collection, and his judgment (especially his generosity to new operas) is not necessarily to be taken as law. But those are only the merest quibbles. He remains one of the few great educator-critics around: sternly witty (Thais' gaudy hammock-bed at the Met ""seemed a hazardous piece of furniture for a courtesan to have""), infectiously curious, and always large-spirited.