These two little pieces, which are but two out of many now known and others yet to be discovered, seem to reveal to us a stage at which the aria form and the binary form merged into the form of movement generally known as the sonata form, which we have chosen arbitrarily to call the triplex. The three distinct sections, the last repeating the first, seem modelled on the aria. The highly organized harmonic life seems inherited from the binary form of the dance movements of the suite. Finally the arrangement and development of two distinct figures or subjects on this plan are proper to the new form alone. Upon this hybrid foundation Pergolesi built up his ‘singing allegro.’ Where Scarlatti had employed figures, Pergolesi employed melodies. Therefore we find a melody in the tonic key, a melody in the dominant, these two constituting with the measures which accomplish the modulation between them, the first section, which is repeated. Then follows a section of free modulation, in which fragments of either melody, but chiefly of the first, play their parts; and lastly the return of both melodies in the tonic key. It is the Italian love of melody which gives it its final stamp. To this love Scarlatti hardly felt free to abandon himself in his harpsichord music; partly, probably, because of the ancient polyphonic tradition which still demanded of organ and of harpsichord music the constant movement we find in the preludes of Bach’s English suites; also because as a virtuoso he was interested in making his instrument speak brilliantly, and because he realized that the harpsichord was really unfitted to melody. But the singing allegro of Pergolesi won the world at a stroke, and almost at once we find it applied to the harpsichord by the young amateur, Domenico Alberti. One should give the devil his due. Poor Alberti, hardly more than a youth, for having supposedly seduced the world of composers to bite the juicy apple of what is called the Alberti bass, has been excoriated by all soberminded critics and treated with unveiled contempt. Let us look into his life and works for a moment.