People say of such-and-such a painter that he has great command of his brush. Might it not be more correct to say that he is controlled of his brush? Merely for the satisfaction of his vanity, to paint brilliantly and display skill with the brush, he has sacrificed the nobler considerations of naturalness and truth – and thus achieved sorry fame as a brilliant technician.

from his writings Thoughts on Art, Caspar David Friedrich; as quoted in Letters of the great artists – from Blake to Pollock, Richard Friedenthal, Thames and Hudson, London, 1963, p. 32