Beethoven on dynamic markings

There is a story I read (can’t remember which book) where some famous pianist/composer sent Beethoven a letter asking him about dynamic markings for a piano piece. He received no answer so he wrote again and again a 3rd time. Finally Ludwig answered him scathingly with words to the effect of “Do you think I’m such an idiot that I would play it twice the same way? Play it how you feel it!” So much for purism.