Since light is best expressed through differences in color quality, color should not be handled as a tonal gradation, to produce the effect of light. Search for the Real and Other Essays (1948)
The impressionistic method leads into a complete splitting and dissolution of all areas involved in the composition, and color is used to create an overall effect of light. The color is, through such a shading down from the highest light in the deepest shadows, sacrified an degraded to a (black-and-white) function. This leads to the destructions of the color as color.