But there is one exception even among these exceptions: the Italian composer Domenico Scarlatti (1685 - 1757) is known only for his music for harpsichord. What makes that different from, say, Chopin? Chopin wrote in many very different genres for the piano. There were large forms like the sonata, medium ones like the ballade and scherzo and small ones like the mazurka and waltz. But Scarlatti, in his later years at least, wrote not only for the harpsichord alone, he also confined himself to one and one form only: sonatas, sometimes called essercizi or 'studies'. In his early years it appeared as though he would follow in the footsteps of his father, Alessandro Scarlatti, a well-known composer of opera seria. But in 1719 he became maestro di cappella at the cathedral of Lisbon where he also taught Maria Barbara, a gifted keyboard player and the crown princess. In 1728 she married Fernando, crown prince of Spain. Scarlatti followed her and spent his remaining years as a retainer in Madrid, free to compose whatever he wanted. His audience was really just two people: himself and Maria Barbara--oh, and whatever members of the court they chose to play for.
Driven by his own musical curiosity and imagination he ended up writing a prodigious five hundred and fifty-five sonatas. 555! They all fell into the basic form of the 18th century instrumental piece: two halves, each repeated. He called his method of composition "ingenious jesting with art" and it was really something quite new. These sonatas were quite unknown to the world at large until a selection was published in 1739. Indeed, you might say that Scarlatti's career as a composer did not really 'take off' until then. Scarlatti is something of a composer's composer and for much of the 19th century he was known only among keyboard cognoscenti. But in the 20th century he came into his own and his sonatas very frequently appear in piano, harpsichord and guitar recitals.
What makes the sonatas so interesting musically? They are often showy and virtuosic, and the way they use the basic two-part form shows amazing diversity, but the two elements that stand out are the harmonic flamboyance and the way they often invoke the colors of Spanish music--and by that I mean the flavor of the guitar.
Here is an example with some of that flavor. The sudden shifts from an A major chord to a G minor chord, with the Bb emphasized suggest Phrygian mode, common in flamenco, and the repeated clusters of D/E also suggest an open string of the guitar, sounding against changing harmony in the other voices. This is the Sonata, K. 105 (from the numbering of Ralph Kirkpatrick):
The rhythm of that sonata might even suggest the flamenco form of the polo. Sonatas could even suggest an aria as this one, often played on guitar:
Leo Brouwer recorded an entire album of Scarlatti sonatas. Notice the delightful ornaments on the repeats. Another sonata that comes across wonderfully on guitar is K. 213, here in a dramatic performance by John Williams.
One of the most adventurous sonatas is K. 264 in E major which features harmonies a tritone away from the tonic and even requires changing from a key signature of four sharps to one of four flats for part of the score.
One of my favorites is the haunting and quirky K. 544. Here is Leo Brouwer again:
And for comparison, on fortepiano:
Finally, a rambunctious fast sonata to close with--and a favorite on piano, here is Ivo Pogorelich with K. 159: