Having ransacked all databases (ie, ninety seconds with Wikipedia) I am unable to pin down a more profound definition of the concerto than the most obvious: a solo instrument (occasionally more than one) playing brilliant passages against an orchestral background. Handel muddied the water with his concerti grossi and Bartok even more so with his Concerto for Orchestra but neither significantly moved the goalposts.
Tone Deaf remains opposed to music that is showy for the sake of being showy. It’s one reason I still can’t take Rossini and it’s why I struggled with Liszt until finding Années de Pélérinage. Also – whisper it not in Gath – why I used to resent piano and (especially) violin concerti. Don’t get me wrong, I have evolved and the Sibelius violin concerto is now Top Ten. But in my callow years I felt the soloist was saying “Bet you can’t do this.” to the orchestra. In effect taunting those worthies.
And there was the cadenza mystique, where everyone worshipfully stopped music-making so that the soloist could run up and down the scales in a virtuosic (ie, frequently vulgar) manner. OK, I’m over that and Beethoven Four and Brahms Two are part of my heart-beat.
But it’s why the Mozart clarinet concerto is my favourite example of that form. Not that it isn’t technically demanding – that’s why Benny Goodman, the great swing clarinettist, recorded it. It’s just that the liquorice stick seems to integrate so well with its accompanying fellows. It doesn’t compete and no cadenza was written for it. One reason may be it is very late Mozart, K622, finished a month or so before he died. I trust this is no great discovery for TD faithful but if not, please try it. Reassuring music to wake up to: today I shall live!