Rameau may have begun in mid-life as the challenger in the battle with the Lullistes. But before he was done, he was the champion of French music in its periodic battles with Italian music, which in generation after generation was regarded by the French establishment as loud, splashy, and inflammatory, much like rock and roll in 1960s America. What finally threw Rameau's music into the shade, years after the composer himself departed, was the self-conscious internationalism of Christoph Willibald Gluck. The Czech-born Gluck had worked in opera in Italy, Germany, and London (where he was briefly held up as an operatic rival to Handel in the 1740s) and then became a musical fixture in Vienna before undertaking the conquest of Paris in the 1770s.

Gluck is best known today for what are called the "Gluck Reforms," changes in the rigid conventions of Italian opera seria. Contemporaries would immediately have noted his integration of recitative and aria, his use of arias and choruses to move the plot, and his elimination of stereotyped arias about generalized mental or emotional states, not specifically referring to the plot. (Singers actually carried favorite "baggage arias" around with them, to be inserted into whatever opera they were singing wherever they fit.) Many of the "reforms" had the effect of bringing Italian opera closer to Rameau-style French opera, which is one reason that Paris warmed to Gluck.

To ears versed in 18th-century music, the most remarkable aspect of Gluck's vocal writing is the absence of virtuosic passagework. Had Handel or Vivaldi written Clytemnestre's aria summoning Jupiter's thunderbolts in Iphigénie en Aulide, it would likely have been full of running 16th notes for the singer. Singing fast was considered exciting and expressive - just as singing high and loud is now - and fast execution was as much a part of what made a singer great as it was part of what made a violinist great. Composing an entire opera without virtuoso singing in Gluck's day was a drastic departure from convention, like composing a piano or violin concerto that didn't demand virtuoso playing. (Lest we dismiss Baroque virtuosity as a tool of superficial musical minds or a catering to primitive musical tastes, keep in mind that Bach's church music is full of such writing.) While Gluck, after hearing a lifetime's worth of 16th notes, had concluded that they didn't do much dramatically, he didn't immediately sway everyone to that opinion. Mozart, even late in his career, wrote arias as flashy as any baroque composer produced. What really killed virtuoso singing was the bigger sound required of singers as halls got bigger and instruments got louder, forcing opera singers to become weight-lifters rather than sprinters.

To the generations that followed him, Gluck was the opera composer. His influence is found not only in the structure of opera, but in lots of the details, as Gluck's more characteristic scenes became archetypes. Berlioz idolized Gluck and modeled his operas after Gluck's. Mozart's statue music in Don Giovanni is obviously indebted to the oracle's pronouncement in Alceste. The debt that the middle movement of Beethoven's Fourth Piano Concerto owes to the underworld scene in Gluck's Orfeo ed Euridice is equally obvious, as Schumann and Liszt noted.

- Lawyer and lutenist Howard Posner also annotates programs for the Salzburg Festival.