=The Aria=.—Scarlatti was not the inventor of the aria or air for the single voice in the meaning of the term as applied to a certain fixed form. Other composers had used it before him in its essential principles, but he was the _first_ to _formulate_ it into a persistent _type_, which it retained for nearly a century, despite its undramatic character. The Scarlatti aria consisted of three parts: two contrasting sections, concluding with a Da Capo or repetition of the first, expressed by the formula A B A. The principle of Repetition as an element of form is now a commonplace, but at the time it was a novelty, and the emphasis given to it by the aria fascinated the public and made it the principal feature of the opera. More than anything else, it led to its degeneration. Singers found in the aria a means of displaying their technical skill; it became the canvas on which they embroidered the most astonishing _tours de force_. The art of acting almost disappeared from the operatic stage; the poise of body and voice required for such vocal efforts banished all but a few conventional gestures. =The Overture=.—Scarlatti’s powers were by no means confined to writing for the voice; the instrumental portions of his works give evidence of equal mastery, though the popular taste for singing allowed him but little scope for extension in this direction. His overtures in particular show a great advance over the simple preludes of the early Italian operas. He perfected what is known as the Italian Overture in contradistinction to the earlier form invented by Lully, and called the French Overture. It consisted of three movements, the first and last quick, the middle movement slow. In its arrangement, this was the direct precursor of the modern symphony. At first the two terms were interchangeable; an overture when played before an opera was called a _Sinfonia_, and curiously enough, when played independently as a concert number it was frequently called an overture. Some of the early symphonies were even printed with one title outside and the other inside.