From the book “Landscape Painting.” In discussion on painting methodologies:
“The last of the four systems mentioned and one which has gradually come to be adopted by the vast majority of our best landscape painters is one in which vibration is obtained by means of a cool overtone painted freshly into a warm undertone, care being taken not to mix or blend the two coats and not to cover up completely the under-tone, rather letting it show through brokenly all over the canvas; the vibration being secured, naturally, by the separate play of the warm and the cold notes. Neither alone would accomplish this purpose, nor would the neutral gray that would result from a too thorough mixing of the tones in the final brush-work.“