126. The study of tones and tone-relations means the study of
pigment-materials and their effects, to find out what quantities
of light we can produce, what qualities of color, what intensities
of color, what neutralizations. That is the problem of tones and
tone-relations. We cannot know much about tones and tone-relations
until we have had experience in the use of pigment-materials. We must
be able to distinguish tones, however slight the differences of value
or of color or of color-intensity, and we must be able to produce tones
according to our discriminations: this with exact precision. In order
to think in tone-relations we must have definite ideas of tone and of
tone-relations, in the form of visual images. In order to express our
ideas we must be able to paint. We must have practice in painting and
a great deal of it. I propose to describe this practice in tones and
tone-relations: what it ought to be, what forms it should take.