AN OLDER FRIEND once advised me, soon after my graduation from college, that if I wished to learn the art of reviewing I should study James Agee on film, Randall Jarrell on poetry, and Virgil Thomson on music. It was the most useful literary advice I've ever received. Reason enough, then, for me to rejoice that the best work of our best music critic is again handily available in A Virgil Thomson Reader.

Not that he is just a music critic: at 85 Thomson rests easily among the finest and most respected American composers. His first triumph, the opera Four Saints in Three Acts (1934)--libretto by Gertrude Stein, direction by John Houseman, choreography by Frederick Ashton and starring an all-black cast--made him famous overnight. Since then, game for anything, Thomson has composed scores for documentaries (he received a Pulitzer for The Louisiana Story), musical portraits of friends, another opera, song cycles, ballet music.

Throughout this time he was also writing the work reprinted here--criticism, an autobiography, a history of 20th-century American composers. Like his music, Thomson's prose is simple and direct, above all carefully descriptive (he strongly advocates the exact adjective), and a sprightly mingling of the scholarly and slangy. And the wickedly funny.

For instance, Thomson's very first concert review for The New York Herald Tribune opens with a critique, not of the concert proper but of the way the orchestra played The Star-Spangled Banner. "The anthem, to me, sounded logy and coarse; it lacked the buoyancy and the sweep that are its finest musical qualities." The next day he topped this outrage by coolly reporting: "At the back of every conductor's mind is a desire to make his orchestra produce a louder noise than anyone else's orchestra can produce, a really majestic noise, a Niagara Falls of sound. At some time in the course of nearly every concert this desire overpowers him. You can tell when it is coming on by the way he goes into a brief convulsion at that point. The convulsion is useful to the conductor, because it prevents his hearing what the orchestra really sounds like while his fit is on."

But to my mind, The State of Music (1939) remains the masterpiece, a contemporary American equivalent to Cyril Connolly's Enemies of Promise. In it Thomson describes musicians trying to live, eat and still produce, debunks the appreciation racket, lambastes academicism, exhorts composers and performers to wrest control of their work from the corporate bigwigs. The most delectable and scandalous sections, however, anatomize the manners and morals of artists, composers and poets.

"If a lady of means really wants an artistic husband, a composer is about the best bet, I imagine. Painters are notoriously unfaithful, and they don't age gracefully. They dry up and sour. Sculptors are of an incredible stupidity. Poets are either too violent or too tame, and terrifyingly expensive. Also, due to the exhausting nature of their early lives, they are likely to be impotent after forty. Pianists and singers are megalomaniacs; conductors worse. Besides, executants don't stay home enough. The composer, of all art-workers in the vineyard, has the prettiest manners and ripens the most satisfactorily. His intellectual and his amorous powers seldom give out completely before death. His musical powers not uncommonly increase."

Whether one has progressed beyond the dodecaphonic or remained at do-re-mi, A Virgil Thomson Reader will give pleasurable instruction and should consequently be read adagio--slowly and leisurely.