Scarlatti's genius for melody modified the still though dramatically correct recitative, and substituted airs in its place. He introduced measured recitative for the first time, and invented the "de capo aria", his singers thus distracting attention from the important dramatic meaning. His knowledge of counterpoint aided him in the construction of the bass, and elaboration of accompaniments. He tired of the monotony of uninterrupted recitative, and organized three forms:-- 1. Recitative secco for ordinary business. 2. Recitative stromentato which was accompanied and used for violent emotion, and used the "thorough bass" by the harpsichord to aid this passionate form of declamation. The sense of the verbal text was enforced by continual interposition of orchestral symphonies. 3. The aria, to which he added the "de capo"--that is, the repetition of the second part following the first. Cavalli employed the ritornello constantly to relieve the monotony of continuous recitative, and introduced repetition in his ariettas, which was disapproved by the Florentine Caccini, who was the father of a new order of music, a style of melody which is not melody; a recitative melody, noble in character and surpassing the songs of the people, not altering the words nor depriving them of life, but augmenting them and giving them meaning and force. Purcell had true dramatic instinct and a declamatory recitative second only to that of Wagner, and his airs show unfettered melody. The laws of his time, which he chose to disregard and modify, are interesting. I. The number of characters was six, three women and three men. a. Prima Donna (soprano). b. A contralto. c. An artificial or male soprano. d. An artificial alto. e. A tenor. f. A bass. II. (a) "Aria Cantabile" was quiet and slow with opportunities of ornamentation, accompanied by a figured bass under pathos. (b) "Aria di portamento" in slow movement and marked rythm was sometimes accompanied only by one or two violins. (c) "Aria di mezzo carattere" had the second part faster than the first, and the accompaniment was rich and varied. (d) "Aria Parlante" was elaborately declamatory. (e) "Aria di bravura" was allegro with brilliant divisions. III. There were three acts and every scene terminated with an air. Every member sang one air but no one sang two airs in succession and no two airs of the same type followed each other. The most important ones came at the conclusion of the first and second act and here the hero and heroine claimed a grand scene, with accompanied recitative followed by "aria d'agilita" and then united in a grand duet. The third act ended with a chorus of lively movement frequently accompanied by a dance. There were no trios, quartets or other concentrated movements allowed, though three characters could join in harmonized exclamation at close of the recitative.