Gluck (1714-1787) came with a regenerating mission. A century and a half's growth of opera in Italy had reduced it to a mere exhibition of singing, and to restore it to something of an embodiment of all the arts--architecture, painting, poetry, music, and dancing--was Gluck's mission. His reformed style, as given in _Orfeo_ (1762), and later in _Alceste_ (1767), certainly justified his demand for reform, and will always entitle him to be called "the saviour of opera." His influence bore more upon the French opera than the Italian, however, and it was left to his great contemporary Piccini (1728-1800) to bring the old Italian model up to the date of Gluck's new style. To this end he effected improvements in the _arias_, duets, and vocal pieces, curtailed the repeats, employed several themes instead of one for his _finali_, all of which tended to put a new complexion on Italian opera. Then arose Spontini (1784-1851), who advanced the dramatic side of opera; Rossini (1792-1868), insisting upon larger choruses and the strengthening of the wind and brass department of the orchestra; with, finally, Donizetti (1797-1848), and Bellini (1802-1835), whose melodic exuberance simply embarrassed and vitiated Italian opera.
Such, briefly, is the story of the rise and development of Italian opera, which, thanks to the labours of his great predecessors, was a reasonably complete art-form long before Verdi scored his first operatic success with _Nabucco_, albeit it had not many characteristics which it now has. The First period Verdi had no great need to improve, or add to, the structure of opera; what was before him chiefly was the work of embellishing and highly colouring the edifice of dramatic musical art (though we know he did immeasurably more)--a labour for which his rare sense of colour and combination peculiarly fitted him.
Verdi's starting point was where Rossini, Mercadante, Donizetti, and Bellini had left Italian opera; and, but for circumstances quite outside himself, he might have gone on writing operas of the _Ernani_, _I Lombardi_, and _Il Trovatore_ type, leaving his later grander efforts, his _chefs d'œuvre_, unwritten. But a great object appeared suddenly in the musical firmament. Wagner (1813-1883), with his train of fads and fancies, swept across the horizon, leaving unmistakable traces of his passage. At first, content with the old traditional opera--with which he might have done wonders--this vast genius set about advancing and propagating unusual ideas concerning operatic usage and creation. The established forms and systems were chiefly attacked.