h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

I can't recall hearing Beethoven's "Eroica"
symphony referred as a sonata before. Or any
other symphony, for that matter.

generally, when people refer to a musical composition
as a "sonata," they usually have one of three things
in mind:

1. A trio sonata (the Corelli op. 1-4 are good examples),
in which three instruments perform, usually with the
bass provided by a harpsichord or low-voiced string
instrument.

2. A work for solo instrument, usually piano or harpsichord
or organ, but occasionally cello (as in J.S. Bach's unaccompanied
suites for cello) or lute (J.S. Bach again ), or other
instrument as the spirit moves.

3. A duet in which one instrument predominates, accompanied
by a keyboard instrument such as harpsichord or piano.
Numerous examples abound. Bach wrote sonatas for flute,
violin, and other instruments. Mozart wrote many charming
violin sonatas, as did Beethoven. Later composers have given
the world cello sonatas, harp sonatas, oboe sonatas, clarinet
sonatas, bassoon sonatas, etc., etc.

When you think about it, A symphony is but a sonata - for orchestra rather than for one or two solo instruments. Likewise a concerto is a sonata for solo and orchestra, and a string quartet is a sonata for four stringed instruments. And so on through quintet to nonet.

They are all sonatas! It is true there are minor genre differences, e.g. that a concerto usually has no minuet or scherzo, but taken all round, once you understand the structure of any one of the above, you should be reasonably comfortable with the others. It then comes down to your preference for a particular medium. Me, I love them all.