Thomas Moran is one of the few painters who understands the importance of establishing transitions from foreground to background, and he uses it to such exaggerated effect here that I share it as an exemplary model to be studied. They are effects that are hinted at in Ted Seth Jacobs’ Light for the Artist. It is an effect that I always look for in oil paintings, actually it’s the most important quality for oil paintings to have, and I try to buy them when I see it.
The above is Thomas Moran’s Chasm of the Colorado (1873-4) in NGA, Washington D.C.
You can then see how John Linnell subtly applies this effect to both sides of his sitter, on the red of his chair and shoulder, and from the right cheek to shoulder:
Here Eugenio Balbiano di Colcavagno uses it where the sun breaks through the columns and arches on the upper-left and center:
Here an anonymous artist uses it where the light emerges from the pedestal’s right side:
Finally, we come to Vermeer’s Officer and the Laughing Girl, where, like Thomas Moran, you can find the effect applied throughout. Note especially the small hole created by the officer’s arm from where the light on the table glows with reflected light: