Frank Fowler, Drawing in charcoal and crayon for the use of students and schools (1885)
“ For example, in drawing or painting a landscape we look at the tone of the trees against the sky and observe which is the darker. If a stormy, heavy sky is seen behind light, feathery, green trees we see that the sky is darker in value.If, on the contrary, trees with dark, rich foliage are observed to be strongly relieved against a bright, sunny sky, we perceive at once that the sky is lighter in value than the trees. ”
