Ooh, they have the manuscript for Rhapsody in Blue, which is in public domain. :) https://imslp.org/wiki/Rhapsody_in_Blue_(Gershwin%2C_George) https://imslp.or

Ooh, they have the manuscript for Rhapsody in Blue, which is in public domain. :) https://imslp.org/wiki/Rhapsody_in_Blue_(Gershwin%2C_George) https://imslp.org/wiki/Rhapsody_in_Blue_(Gershwin%2C_George) Ha-- he's got a single grand staff for "jazz band" and just names the instruments inline. Judging by the historical recordings, that included an extra piano for the jazz pianist to noodle around on, which is kind of funny to see on stage. Sometimes people will throw in a banjo, too. Also-- if you've ever had the experience of trying to remember a song and singing things in your head in the wrong order-- so did George Gershwin! You can see where he crossed out a small piano solo excerpt and then wrote it back in after a little interlude with piano and French horn. I.e., "oops, that's supposed to come later," or perhaps, "hm, this section needs to be longer, let me insert a little thingy with a drone in l.h. and French horn inner line. Yeah, that's good..." Near the beginning he appears to have initially considered a hacky little Lisztian rising chromatic scale that alternates with a repeated octave in the bass. That apparently was supposed to lead the band playing the main theme, very soon after they already played it. He crossed out the entire thing and replaced it with an echo of the little syncopated mumble, followed by an imitation of the opening clarinet scale. Then he has a more elegant re-harmonization (changing the chords) of the main theme and a little subtle interplay between piano and jazz band. This is followed by a fairly long cadenza, and then he finally brings the jazz band back in with a full statement of the theme. You can literally see the signs of him throwing out a simple song form with a short solo break and turning it into a more substantial through-composed form. Almost like he got stuck, went and listened to (or played) Tchaikovsky's Piano Concert No. 1, then came back and finished the piece! Apparently, Gershwin actually improvised on top of what's written here for the debut. IIRC Marcus Roberts did the same in a live performance some years back. I'm impressed by anyone who can do that live; however, he didn't really stay in the Gershwin style for his cadenzas. Gershwin's improvisations are these idiosyncratic little polyrhythmic automatons, drawing heavily on stride style as well as popular syncopated and dance rhythms of his era. And in Rhapsody you'd have to fit that in with the classical-style arabesques. It's got to be something like musical "method acting" to be able to pull this off. And bonus points if the improviser can throw in some subtle R&B or rap references in the improvisations. :)