If the stroke of the brush is so important, it is because it expresses precisely what is not there.

('CF, p. 44); as quoted in Karel Appel, a gesture of colour, eds. by Jean-François Lyotard, Christine Buci-Glucksmann, Herman Parret, Leuven University Press, 2009, p. 69 - from 'Karel Appel, a gesture of colour' (2009)