... it may be said that choice of palette is a matter of temperament. Each student must experiment with the various pigments and select those which he personally finds most sympathetic. But, in general, it is best to eliminate all the secondary or compound colors, such as green, purple, etc.; and this for two reasons: first, because a painter secures more vibration in his work by mixing his own secondary and tertiary tones; and, second, because if one has a green on the palette, one is very apt to use that special green, instead of searching out the various greens (and they are infinite) that may enter into his picture motive. It may also be stated as an axiom, that the more experienced the artist, the more limited is his palette. The expert cannot be bothered with useless pigments. He selects the few that are really essential and throws aside the rest as useless lumber. The distinguished Swedish artist, Zorn, uses but two colors- vermilion and yellow ochre; his two other pigments, black and white, being the negation of color. With this palette, simple to the point of poverty, he nevertheless finds it possible to paint an immense variety of landscape and figure subjects, and I have never heard his color criticized as being anemic or lacking in power. Many other painters limit themselves to five colors; and when the palette is extended beyond seven, it is safe to presume that one is skirting the borders either of the amateur or the student class.
Birge Harrison, Landscape Painting, 1909