We have spoken of the _da capo_ form and its unfortunate influence on the monodic style. Strictly speaking, the term _da capo_ was not used until Tenaglia used it in his opera _Cleano_, in 1661. But the ordinary statement that the _da capo_ was invented by Tenaglia (or by Alessandro Scarlatti, as is more frequently said) is quite misleading. Tenaglia’s _da capo_ aria is of little historical importance. The composer used the term probably not out of a sense of form, but out of pure laziness, preferring not to copy out the opening section a second time. The real _da capo_, which in its more developed state becomes the sonata form, can be traced back vaguely into primitive music, and exists in miniature perfection in many folk-songs. It becomes a recognized mold for musical composition about the time of Monteverdi. With the later opera and oratorio composers we find it in a debased state, where it exists not as an artistic form but as a mere stenographic convenience. This debasement is typical of the cheapening of opera which continued pretty steadily up to the time of Gluck. The coloratura aria obscured to all minds the expressive possibilities of the _stile rappresentativo_, and left to song nothing but the old madrigal tradition fused with certain elements of popular feeling. The many arias, ariettas, _canzoni_, _cantate_, and even one-voiced madrigals, which were published by the fashionable composers of the seventeenth and eighteenth centuries showed little regard for dramatic or precise emotional expression, but continued to sing with the placid lyrical feeling of the great madrigal age. They were only obliged, with the growth of solo singing, to become clearer as to form, more regular in metre and line. For their ability to achieve this they had the popular song almost wholly to thank. Scarlatti’s beautiful _canzonetta_, _O cessate di piagarmi_, with its simple guitar accompaniment, might pass for a Neapolitan folk-song of to-day. Yet, on the whole, the solo songs of this period failed to fulfill the high artistic promise of the early seventeenth century.