or interludes. Recitative, without abandoning its distinctive characteristics, became more strongly accentuated, and in process of time passed over into song. Such vocal melodies as seemed thus to be called forth by the emotions of the situations were called _cavata_ or _cavatina_. At first they were {RECITATIVE--THE ARIA.} (161) considered as an ingredient or embellishment of the recitative, but later on they were treated independently. _Arioso_ in the recitative indicates an interpolated passage of vocal melody. A rapid alternation of varied or contending emotions in monologue or dialogue called for accompanied recitative, which generally passed into a song, where a definite emotion might find its due expression. It was here that singers and composers sought to accomplish the highest degree of dramatic expression, and although in the aria they might be tempted to an undue regard for musical display, to the neglect of dramatic effect, here at least they strove for a faithful portrayal of human sentiment. The aria was the almost exclusive form given to regular artistic song. Choruses, which formerly concluded every act, were afterwards only exceptionally employed, generally when the occasion, being a court festivity, required additional outward show; they very seldom formed an integral part of the performance.[13] Ballets, which were originally combined with the choruses, became by degrees quite distinct, and were given between the acts of the opera. Concerted vocal pieces were confined within limits more and more strictly defined, until the rule came to be that in every opera there should be a duet for the prima donna and the primo uomo, and a terzet in which the primo tenore also took part; even the places for these, at the end of the second and third acts, were appointed. Further restrictions were imposed on the character of these concerted pieces by the necessity of giving all possible effect to the voices. They do not pretend to represent a conflict of struggling passions, pressing onward to the catastrophe; rather does some definite mood, the natural result of the situations which have preceded it, find its fitting expression in their regular concerted form, which affords ample scope for the display of varieties in quality and style of the individual voices. The aria, which gave expression to a fixed lyrical mood, was seldom the culminating point of a dramatic situation; its connection with the action of the piece was, for the most {OPERA SERIA.} (162)