Contrive that the trees in your landscape be half in shadow and half in the light. It is better to represent them as when the sun is veiled with thin clouds, because in that case the trees receive a general light from the sky, and are darkest in those parts which are nearest to the earth.
Chap. CCCXXVI.—Of the Green of the Country.
Of the greens seen in the country, that of trees and other plants will appear darker than that of fields and meadows, though they may happen to be of the same quality.
Chap. CCCXXVII.—What Greens will appear most of a blueish Cast.
Those greens will appear to approach nearest to blue which are of the darkest shade when remote. This is proved by the seventh proposition[83], which says, that blue is composed of black and white seen at a great distance.
Chap. CCCXXVIII.—The Colour of the Sea from different Aspects.
When the sea is a little ruffled it has no sameness of colour; for whoever looks at it from the shore, will see it of a dark colour, in a greater degree as it approaches towards the horizon, and will perceive also certain lights moving slowly on the surface like a flock of sheep. Whoever looks at the sea from on board a ship, at a distance from the land, sees it blue. Near the shore it appears darkish, on account of the colour of the earth reflected by the water, as in a looking-glass; but at sea the azure of the air is reflected to the eye by the waves in the same manner.
Chap. CCCXXIX.—Why the same Prospect appears larger at some Times than at others.
Objects in the country appear sometimes larger and sometimes smaller than they actually are, from the circumstance of the air interposed between the eye and the horizon, happening to be either thicker or thinner than usual.
Of two horizons equally distant from the eye, that which is seen through the thicker air will appear farther removed; and the other will seem nearer, being seen through a thinner air.