„The advance from drawing to painting should be gradual, and no serious attempts in colour should be made until the student has obtained proficiency in outline and in light and shade. If the artist cannot draws objects in a rather masterly way there is no point in his attempting colour.“
— Ogden Rood American physicist 1831 - 1902
Students' Text-book of Color; Or, Modern Chromatics, with Applications to Art and Industry. New York: D. Appleton and Company. 1881.