Apparently the libretto that Mozart used for La Clemenza di Tito – the one by Pietro Metastasio, with revisions for Mozart by Caterino Mazzolá – was one of those bike-share libretti of the eighteenth century, in the sense that pretty much everyone took a ride, if by everyone we understand Mozart, Gluck and Josef Mysliveček.
Some arias from the Gluck version, particularly “se mai senti spirarti sul volto,” are recital staples.
Here’s the inimitable Joyce DiDonato singing “se mai senti”:
And here below is another version which might be from the Mysliveček opera, or – which seems more likely given how it sounds – might be the Baldassare Galuppi version (he wrote one too!) but I am not sure because it doesn’t say who the composer is on the YT clip and IMSLP doesn’t have the score for Mysliveček’s or Galuppi’s Tito, so I couldn’t check. Or the music might be some other party that I have overlooked entirely. As I said, everyone appears to have had a go at this libretto.
The text has a few words different from the version Gluck used, but it’s basically the same. The music, though, is quite different, with that softly drumming pizzicato rather than Gluck’s prettily winding oboe part. And the singer here is a soprano named Roberta Invernizzi who, as one of the YT commenters so succinctly put it, “nailed this aria.” The sound is bright and clear and luminous.
In the above versions Sesto is bidding goodbye to Vitellia in solo aria form.
In the Mozart version the text is a little different and the music is too – we have not a “goodbye, baby” aria but rather the beginning of a “goodbye, baby” aria which then launches itself into a trio. (I never noticed before, but like Gluck, Mozart starts off with an oboe.)
It’s “se al volto mai ti senti” rather than “se mai senti spirarti sul volto” but the text means essentially the same thing, about Vitellia feeling Sesto’s dying breath as a little breeze on her face.
I was curious to hear more of the Gluck version, but after a significant time (about ten minutes; I am not a patient person) spent trawling on YouTube, I couldn’t fund much more of it other than the overture and this aria for Tito, “di quel sublime soglio,” a.k.a. “del piú sublime soglio” in the Mozart version. Bummer.