Carl Czerny,
Letters to a Young Lady
(1839)
“ From every musical instrument we may produce either a fine tone or a detestable one, according as we handle it. The same excellent violin which, in the hands of a clever player, sounds so delightfully, will, when handled by a clumsy person, yield as disagreeable sounds as if a number of kittens were squalling. It is the same with the pianoforte. If it is not properly handled by the player, or if we merely thump and bang the keys, the best instrument will sound hard and unpleasant. ”
