With pigments and pigment-mixtures we are able to produce a great number and variety of effects, effects of light and of color, which we call the tones of the palette. In every tone thus produced there are two elements: there is the quantity of light in the tone that we call its value, and the quality of light in the tone that we call its color. The quantity of light in any tone and its color depend upon the pigments which we use in producing it. When two or more pigments are used, the tone depends, not only on the pig ments but on the quantities and proportions of them that are used.