Music: Porgy into Opera

On the bare, dusty stage of Manhattan's Guild Theatre last week 75 Negroes sang, swayed, rolled their dice, exultantly prayed to "de Lawd." In the darkened pit lean Rouben Mamoulian, cinema director, tapped on an old-fashioned schoolteacher's bell, interrupted them constantly with "All right, children. . . ." His stage pictures grew steadily in beauty while the tempo of the acting rose to fever pitch.

Five blocks away in Carnegie Hall orchestramen in shirtsleeves rehearsed so relentlessly that a sore-lipped trumpeter had to beg off from...