Concerto Guide: Mozart, Piano Concerto no.9 in E flat major, K 271 "Jeunehomme"

The nickname comes from this concerto being inspired by the visit to Salzburg of a French keyboard virtuoso, Mlle Jeunehomme. It was written in January 1777, the same month that Mozart turned 21, and is coincidentally a musical coming of age. Rosen in his The Classical Style calls this concerto "the first unequivocal masterpiece in a classical style purified of all mannerist traces." By "mannerist" he refers to all the quirky experimentation being done from 1750 to 1775 by C. P. E. Bach and many others.

The very opening of the piece reveals a symmetry, balance and wit that are inherent in the Classical style and disruptive of Baroque continuity:

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The opening fanfare is not so unusual, but having the soloist answer it with a contrasting phrase is. Then both phrases are repeated which underlines both the contrast and the balance. You might notice that the orchestra, in unison, falls an octave from E flat to E flat, then ends on B flat. The piano answers with a B flat rising an octave to B flat, then ending on E flat. Both balance and symmetry with the simplest of means. Mozart (and Haydn) keep showing us over and over that great music is often created with the simplest materials. Another thing that Rosen points out is that the orchestra and the piano are actually in two different meters, though with the same time signature. The orchestra is most definitely in 2/2, while the piano is in 4/4. The effect is for the piano phrase to sound like a hastening or a filling in of the more brusque orchestral fanfare. The orchestral phrase that follows, beginning on the last measure above and continuing:

is a fusion of the two phrases with the first violins creating a synthesis of the two by the subtlest means of contour and accent. This kind of rhythmic subtlety, typical of Haydn and Mozart, was alien to the Baroque conception of rhythm as a simple and unified texture.

This striking solution to the problem of soloist versus orchestra that Mozart solves by having the soloist interrupt the orchestra twice at the very beginning and then not appear again until the end of the orchestral exposition, was so striking that Mozart never used it again. Beethoven did, however, a couple of times. His "Emperor" Concerto begins with the orchestra stating a maestoso chord progression, each member of which is taken over and ornamented by a piano cadenza before the orchestral exposition.

Like the orchestral opening of an opera aria, this exposition does not modulate and the piano enters just towards the end with a trill, accompanying the orchestra:

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 before presenting its exposition which does modulate:

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The piano gives the movement its dramatic energy. For Mozart, the orchestral exposition is passive and the solo one active. We can see in the Mozart concertos for piano how his skill as an opera composer feeds directly into his mastery of the concerto. As Rosen points out in his Sonata Forms, the aria form and the concerto form have a lot to do with one another.

I won't go on and dissect the rest of the movement, but you might have a look at Rosen's The Classical Style, pages 198 to 214 (expanded edition) where he does just that. Instead, let's have a listen to the whole piece. Here is a performance on original instruments by Malcolm Bilson and the English Baroque Soloists conducted by John Eliot Gardiner:

And here is one on modern instruments by Mitsuko Uchida with Jeffrey Tate conducting an unknown ensemble, apparently at the Mozarteum, Salzburg:

UPDATE: Checking back I see that the ensemble is the Mozarteum Orchestra.