Many piano players are curious about the harpsichord, especially those who play a lot of old music like Bach and Haydn from the days when the harpsichord was still around. It’s definitely worth exploring the harpsichord. It’s a beautiful instrument in its own right, but it also will lead you to a much more subtle understanding of how to play this music on the piano.
The harpsichord does not have a sustain pedal. So when we play it we need to cultivate a really fine legato. We need to also develop a really sensitive touch. When we play the piano a hammer hits the string with a complex mechanism. When we play the harpsichord a quill plucks the string with such a simple mechanism that we can feel it in our fingers. With some practice you can change the way that the string is plucked and create very different sounds.
The harpsichord cannot get louder and softer, like a piano, but this does not mean that it is not expressive. We just use different techniques than the piano to express ourselves. These techniques often transfer very well to playing the piano.
We use articulation, that is small changes in the legato, to shape the musical lines. Unlike on the piano, on the harpsichord we usually don’t play all the notes at the same time, and we typically arpeggiate most of the chords.
If you are fortunate enough to have access to a harpsichord try these things out. Be careful that your music does not sound spiky and disjointed. On the harpsichord that is a real danger. If you are at a piano, and playing music by composers who wrote for the harpsichord try out some of these techniques and see if they make the music more expressive and easier to understand.