[Woodduck]

Did Mozart write any through-composed music?

Would you consider the finale to Don Giovanni "Don Giovanni a cenar teco m'invitasti e son venuto" to be through-composed? ... it doesn't seem to me to be a "numbers" piece. it doesn't have that ok we're gonna go through this to get the melody out there... then we can worry bout the drama/repeats/etc.etc.etc later....

Why don't people include this as an example of Mozart's contribution to through-composed music?

Essentially, is there really something else that I'm missing that Wagner's music has that Don Giovanni a cenar teco m'invitasti e son venuto doesn't?

No Mozart opera is through-composed, but short sections of some of them are. And yes, when he does it, he does it well, as he does everything he does. I assume he receives credit for that, though he isn't he first composer to do it. Monteverdi did it (before there was a distinct thing called recitative), and Handel and Gluck did it even though they continued to use recitative.

Wagner increasingly obliterated the distinction between recitative and non-recitative, moving flexibly through the whole continuum between speech rhythms and lyrical song. What his mature music has that Mozart's (or any previous composer's) doesn't is a musical development carried as much, if not more, by the orchestra as by the the vocal lines, which often simply trace one more line in the harmonic texture.

 

[Woodduck]

I'm familiar with many of his operas (although not necesarily very intimately) but this is the only song that has dawned on me as being through composed.

can you think of any other sections of his operas or other large scale works that are through-composed?

I think DavidA is correct about the Act 1 final ensemble in Figaro. I'm not familiar enough with all the other operas to say what might be found in them.

 

[Woodduck]

Yes, it's the Act 2 finale. I believe that sometimes Acts 1 and 2 are performed without intermission.