"..by adding and more adding, you soon get such an accumulation of colour material that the painting eventually acquires a heavy, febrile surface. The danger is of such a thick, abundant, heavy surface seeming dull and sluggish to the eye, because in that case it would lose the mobility, which, for Appel, is the essential quality of all surfaces. Painting blinds painting, like mud and clay blocks a pool. A painting's entire choreography, caught in tension, can collapse in an instant. And it's in that instant when Appel the draughtsman gets to work, and the open play of the lines of the drawing is the right medium to blow new life into the painting."