Wolfgang Amadeus Mozart made his mark on nearly every form of music popular at the end of the 18th century. But, aside from opera, there was one form in which he blew away all his competition, even the venerable Franz Josef ``Papa'' Haydn.
Mozart was unsurpassed in the concerto - a composition for instrumental soloist and orchestra. Between about 1773 and 1791, nobody achieved better-balanced conversations between soloist and orchestra than Mozart.
Concertos would become louder, flashier, ever more dramatic after Mozart's time. But the basic format Mozart used is still frequently employed today. In figuring out how a concerto is put together, it's easiest to go back to Mozart's. Refined, elegant and streamlined, they are among the first mature examples of the concerto as we've come to know it.
Mozart's keyboard concertos - now usually played on the piano, although the early ones were probably first played on an instrument more like a harpsichord - are his finest. But they require some sorting out.
There are 27 numbered keyboard concertos. No. 7 is for three pianos, and No. 10 is for two, which leaves 25 for one piano and orchestra. The first four, as well as three others outside the numbered series, are arrangements of pieces by other composers.
So that leaves 21 original solo keyboard concertos, all of them written over a span of just 17 years, mostly for highly profitable all-Mozart concerts in Vienna in the 1780s, in which the composer himself was the acclaimed soloist.
To confuse matters further, Mozart's works have been cataloged in roughly chronological order, and carry a K. (for Koechel, the cataloger) number. So a Mozart piano concerto can be identified by either of two numbers, or both - Piano Concerto No. 20 in D minor, K.466, for instance. This sort of mess is one reason people are intimidated by classical music even before they've heard a note.
Anyway, the fully mature concertos begin with No. 9, K. 271. These are all fine works, but the most popular are those in the 20s.
Earlier works by composers like Antonio Vivaldi and Giuseppe Torelli established the concerto's floor plan. Mozart's concertos were expansions of that plan. It's as if a typical 10-minute concerto by Vivaldi, with its three movements in a fast-slow-fast pattern, was a nice little apartment with a kitchen, bedroom and bathroom. A typical 30-minute concerto by Mozart would correspond to the same three rooms, built on the scale of a mansion. Later concertos would be even more palatial.
Before Mozart, concertos' fast movements often contained chugging, hyperactive themes, while the slow movements were quiet interludes. The orchestra - usually a small string ensemble - would introduce themes, then the soloist would play the themes, then the orchestra would return with the same music played a little differently, perhaps in a different key, then the soloist would respond, and so on.
When Mozart started writing concertos at the seasoned age of 17, the form was gradually changing. Right then, the orchestra generally opened and closed movements, but in between provided only low-key accompaniment to the spotlighted soloist.
That relationship became more intricate in Mozart. The orchestra never threatened to take over the concerto, but it was always commenting on and answering the soloist's passages, particularly through colorful (for the period) woodwind writing.
The first movement of a typical Mozart keyboard concerto somewhat resembles the first movement of a symphony, with an exposition-development-recapitulation pattern. (For an explanation of that, jump ahead to the Beethoven chapter.)
The big difference between the first movement of a Mozart symphony and the corresponding movement in a Mozart concerto is this: In the middle portion of a concerto's first movement, Mozart has the soloist and orchestra comment on the themes in dialogue; in a symphony, he carefully ``works out'' - develops - the themes in a more abstract style.
And the presentation of themes in a symphony follows a certain scheme of key relationships, a scheme that is greatly simplified in a concerto.
The second, slow movement typically has a flowing, singing quality. This is even more apparent in Mozart's concertos for wind instruments, which are as lyrical as opera arias. The composer's fidgety nature often comes out in the final movement, fast and glittering.
Mozart's concertos are, to a degree, deliberately incomplete. The composer repeats some simple themes again and again without variety, intending the performer to embellish them on the spot, like a jazz musician.
And near the end of every first movement, and often at a similar point in later movements, there comes a cadenza. The orchestra is silenced, and the pianist plays a long, difficult solo passage in which bits of the main themes whirl around.
Because Mozart wrote most of these concertos purely for his own use, he left himself much leeway in performance. Later pianists were unwilling to improvise as freely as Mozart, so many of the cadenzas we hear today were written by later composers or scholars, although a growing number of pianists now bravely improvise in Mozartean style.
Mozart listening suggestions
Pianists tend not to record Mozart concertos unless they have a special sympathy for the music, so it's hard to go wrong with any modern recording featuring a well-known pianist.
For a big, expensive package containing all the concertos, consider the sets featuring pianists Alfred Brendel on Philips or Murray Perahia on CBS/Sony. There's also a sparkling collection on instruments of Mozart's time with Malcolm Bilson on the fortepiano, the piano's immediate ancestor; this is on the Archiv label.
Or pick and choose among individual CDs pairing the later concertos. The packages already mentioned are available as single discs.
Other good choices would be recordings by Mitsuko Uchida on Philips or Vladimir Ashkenazy on London.