Although slight variations in loudness and timbre, or tone colour, can be obtained by differences in the firmness with which the harpsichordist depresses the keys, no sustained crescendos are obtainable by the action of the fingers alone.
If there was a slightly unpleasant surprise for the French at this week's meeting, it was the firmness with which Rudolf Scharping, the German defence minister, reaffirmed the primacy of the American connection.
"In collecting the licence fee the BBC must balance firmness with fairness," said the BBC Trust chairman, Sir Michael Lyons.
One of the jumpsuited operatives stood atop the boards, testing their firmness with apparent satisfaction, while the other quickly loaded the cones into the back of the truck.
It's easy to adjust to the ideal firmness with a handheld remote, and the soft microsuede cover is waterproof and machine washable.
For each potential new variety, she evaluates firmness, perceived with the force of the first bite; crispness, detected as teeth shear an apple's flesh and it cracks; and juiciness, revealed when the flesh is chewed and its cells rupture.
The striking and hopeful thing about the speeches given by the leaders of the major carbon-emitting nations was the firmness with which almost all of them reiterated their unilateral commitment to making significant, if inadequate, cuts in emissions.
Connor Campbell, financial analyst at betting firm Spreadex, said: "It seems that it is going to be hard to provide a tourniquet for sterling's recent wounds given the solidity of the newly announced Brexit timeline... and the firmness with which May stated her intention to chase border control even if it means relinquishing Britain's position in the single market".
