In addition to everything else - composer of astonishing invention and fluency, virtuoso pianist, all-round boy wonder - Wolfgang Amadeus Mozart (1756-1791) was an accomplished violinist and violist. He could hardly have avoided it, as his father Leopold was a master violinist and the author of the leading violin manual of the day.

So it is hardly surprising that Mozart composed a number of sonatas for violin and piano - or rather, for piano with violin. In the duo sonatas that Mozart composed throughout his career, there is a constant development of equality in the partnership, which initially placed the burden entirely on the keyboard and left the string part almost optional.

This progress was well advanced in the summer of 1781, when Mozart gathered a set of six sonatas for publication in his new home, Vienna. (Tellingly, this publication was dedicated to a pianist, Josepha von Auernhammer, not a violinist). "These sonatas are the only ones of their kind," an anonymous reviewer wrote in the Hamburg Magazin der Musik in 1783. "They are rich in new ideas, showing traces of the great musical genius of their author.... Moreover, the violin accompaniment is so ingeniously combined with the piano part that both instruments are continuously employed; and thus these sonatas demand a violinist as accomplished as the pianist."

K. 377, the third of the set, is a vigorous and dramatic work full of surprises. The first movement is driven by the energy of fleet triplets flowing between the instruments as they trade melody and accompaniment. The second movement is an extraordinary set of variations in D minor. The Minuet finale, complete with a contrasting Trio section in B-flat, reduces the violin to its most subservient role.

- John Henken is the Los Angeles Philharmonic Association's Director of Publications.