All the European tendencies at that time are reflected in his operas: the model of Keiser in his early works, the Venetian model in his _Agrippina_, the model of Scarlatti and Steffani in his first early operas; in the London works he soon introduces English influences, particularly in the rhythms. Then it was Bononcini whom he rivalled. Again, those great attempts of genius to create a new musical drama, _Giulio Cesare_, _Tamerlano_, _Orlando_; later on, those charming ballet-operas inspired by France, _Ariodante_, _Alcina_; later still, those operas which point towards the _opéra comique_ and the light style of the second half of the century, _Serse Deidamia_.... Handel continued to try every other style, without making any permanent choice as did Gluck, with whom alone he can be compared. Without doubt (and it is his greatest fault in the theatre) he was constrained by the conventions of the Italian Opera at tunes and by the composition of his troupe of singers to overlook his choruses, and to write operas for solo voices, of which the principal _rôles_ were cast for the Prima Donna and for the contralto,[300] but whenever he could, he wrote his operas with choruses, like _Ariodante_, _Alcina_, and he only owed it to himself that he did not give to the tenor or to the bass their place in the concert of voices.[301] If it was not possible to break the uniformity of the solo voices by the addition of choruses, still he enlivened these solos by the flexibility and the variety of his instrumental accompaniments. Such of his most celebrated airs, as the Garden scene in _Rinaldo_, "_Augelletti che cantate_," are only in truth an orchestral tone picture. The voice mingles itself only as an instrument,[302] and with what art Handel always decides his melodies in disengaging the beautiful lines, drawing all the parts possible in pure tone colours from single instruments, and from the voice isolated,--then united,--and what of his silences! The appeal of his melodies is much more varied than one usually believes. If the _Da Capo_ form abounds in his works,[303] it is necessary to admit that it was practically the only one of that period. In _Almira_, Handel uses the form of a little strophic song, very happily. For this, Keiser supplied him with models, and he never renounces the use of these little melodies, so simple and touching, almost bare, which speak direct to the soul. He seems to return to them even with special predilection in his last operas, _Atalanta_, _Giustina_, _Serse_, _Deidamia_.[304] He gives also to Hasse and to Graun the model of his six cavatinas, airs in two parts,[305] which they later on brought into prominence. We find his dramatic airs also have the second part and the repeat.[306]