I decided to review Harpsichord Technique -- a guide to expressivity by Nancy Metzger. She quotes all the masters who have previously written on the subject--François Couperin, Arnolt Schlick, Girolamo Diruta, Jean-Philippe Rameau, etc.
She recommends something she calls the super legato. From my days as a recorder of midi music I know that the legato is achieved by allowing a note to extend the entire time until the next note starts. With a super legato there is an additional bit of overlap. The two styles produce different effects. To get two of the same note you must release the first before the second begins, so super legato is not possible. In midi this is simple to achieve, but by a live player it takes practice holding the fingers down.
How interesting. More so than organs or pianos there is a lot of difference between one harpsichord and another. It can vary how far the key goes down before the plucker encounters the string. It can vary how hard you push to get the string to pluck. It takes practice with the particular harpsichord to achieve perfection here. I have also been told you should replace all the pluckers at once so there will be consistency in how hard you push from one key to another.
She explains how to get the super legato and provides exercises.
Since the volume doesn't vary on a harpsichord, you are stuck varying the length of the notes relative to one another to get any kind of expression.
She discusses style brisé -- broken chord arpeggiation. This should involve some holding down of the keys -- rather like imitating a sustain pedal, which doesn't exist on the harpsichord.
The short version of this long book is that expression on the harpsichord derives primarily through manipulation of the spaces between the notes. You will be playing primarily music written for the harpsichord, and the composer will have been aware of how this was done.
A modern professional harpsichordist will be required to realize from a figured bass where these expressivity principles will be used in notes of the keyboardist's own invention.
It's a clear and fascinating book.
Why am I writing about this? I believe articulation to be a vital part of expressivity in singing, too, but in a far more complex and subtle way than for a keyboardist. Few singers have any awareness at all of how this features in their own singing. The widest variety in the use of articulation in singing by a wide margin is, of course, to be found in the singing of Cecilia Bartoli. I get the feeling she isn't hanging out with us.