Task: Text Categorization
Input (English): Several of his early works, including such operas as Cleonice, Demofoonte, and Artaserse, were written with librettist Pietro Metastasio. He had begun composing an opera based on the Song of Roland, but the discovery that Niccolo Piccini was given the same libretto to work on sparked a rivalry in the Parisian press and motivated him to compose Armide. Collaboration with the librettist Calzabigi resulted in the composition of the ballets Semiramide and Don Juan, as well as an opera featuring the "Dance of the Blessed Spirits" and another in whose preface he declared his intent to "restrict music to its true office of serving poetry. " FTP, identify this German classical composer of "reform" operas such as Alceste and Orfeo et Euridice.
Output (English): Fine Arts