The art of painting is perhaps the most indiscreet of all the arts. It
is an unimpeachable witness to the moral state of the painter at the
moment when he held the brush. The thing he willed to do he did: that
which he only half-heartedly willed can be seen in his indecisions: that
which he did not will at all is not to be found in his work, whatever
he may say and whatever others may say. A distraction, a moment's
forgetfulness, a glow of warmer feeling, a diminution of insight,
relaxation of attention, a dulling of his love for what he is studying,
the tediousness of painting and the passion for painting, all the shades
of his nature, even to the lapses of his sensibility, all this is told
by the painter's work as clearly as if he were telling it in our ears.
_Fromentin._