“BASIC PRINCIPLES OF COLOR IN NATURE
“When you work outdoors, you only need to worry about a few basic concepts. 1. The nature of the eye, 2. The local color of the object 3. The color of outdoor light, 4. The color of the atmosphere itself, and 5. The effect of neighboring colors on one another.”
Wow! A lot packed into that. Probably, when he mentions the nature of the eye, he is talking about cones, creating colors with bias, and keeping the eye moving. 2-5 seem to speak about the influences that affect the appearance of color. Light, atmosphere, and reflected light all alter the appearance of local color to some degree. But why do we have to worry about all that? Isn’t observation our best guide to what colors are in our complex and changing environment? I’d be surprised if Gruppe meant artists to paint by rule rather than observation, and I saw no sign of the approach of rule in his book. Perhaps he just means us to be aware that all of these factors are present when we observe colors.