Opera seria
By far the most successful librettist of the era was Metastasio, others were Apostolo Zeno, Benedetto Pamphili, Silvio Stampiglia, Antonio Salvi, Pietro Pariati, Pietro Ottoboni, Stefano Benedetto Pallavicino, Nicola Francesco Haym, Domenico Lalli, Paolo Antonio Rolli, Giovanni Claudio Pasquini, Ranieri de' Calzabigi and Giovanni Ambrogio Migliavacca.
[1] A typical opera would start with an instrumental overture of three movements (fast-slow-fast) and then a series of recitatives containing dialogue interspersed with arias expressing the emotions of the character, this pattern only broken by the occasional duet for the leading amatory couple.
After an aria was sung, accompanied by strings and oboe (and sometimes with horns or flutes), the character usually exited the stage, encouraging the audience to applaud.
As response, the Rome-based Academy of Arcadia sought to return Italian opera to what they viewed as neoclassical principles, obeying the classical unities of drama, defined by Aristotle, and replacing "immoral" plots, such as Busenello's for L'incoronazione di Poppea, with highly moral narratives that aimed to instruct, as well as entertain.
However, the often tragic endings of classical drama were rejected out of a sense of decorum: early writers of opera seria librettos such as Apostolo Zeno felt that virtue should be rewarded and shown triumphant, while the antagonists were to be put on their way to remorse.
[1] The age of opera seria corresponded with the rise to prominence of the castrati, often prodigiously gifted male singers who had undergone castration before puberty in order to retain a high, powerful soprano or alto voice backed by decades of rigorous musical training.
Nicola Porpora, (much later to be Haydn's master), set the work to music, and the success was so great that the famed Roman prima donna, Marianna Bulgarelli, "La Romanina", sought out Metastasio, and took him on as her protégé.
On the other hand, Handel, working far outside the mainstream genre, set only a few Metastasio libretti for his London audience, preferring a greater diversity of texts.
Vinci's settings of Didone abbandonata and Artaserse were much praised for their stromento recitative, and he played a crucial part in establishing the new style of melody.
Jommelli's works from 1740 onwards increasingly favored accompanied recitative and greater dynamic contrast, as well as a more prominent role for the orchestra while limiting virtuosic vocal displays.
Gluck paid great attention to orchestration and considerably increased the role of the chorus: he also cut back heavily on exit arias.
By the final decade of the century opera seria as it had been traditionally defined was essentially dead, and the political upheavals that the French Revolution inspired swept it away once and for all.
Opera seria plot-lines are heavily shaped by this criterion: Il re pastore displays the glory of Alexander the Great, while La clemenza di Tito does the same for the Roman emperor Titus.
Sometimes the links between opera and audience were even closer: Gluck's serenata Il Parnaso confuso was first performed at Vienna with a cast consisting of members of the royal family.
However, with the French Revolution came serious political upheavals across Italy, and as new, more egalitarian republics were established and old autocracies fell away, the Arcadian ideals of opera seria seemed increasingly irrelevant.
