I was always told a piano is a percussion instrument because a hammer hits the strings but a harpsichord is a string instrument because the strings are plucked. Certainly the categorization of these instruments is both arbitrary and academic, but it does explain a lot about how they sound. Esp. the
lautenwerck or lute-harpsichord which uses gut strings and sure sounds like some kind of guitar or lute to me.

16/44 FLAC download
Listening to the Well Tempered Clavier on
das lautenwerck is interesting, but not something I do very often.