A Treatise on Painting/Chapter 289
Chap. CCLXXXIX.—Of the Change observable in the same Colour, according to its Distance from the Eye.
Among several colours of the same nature, that which is the nearest to the eye will alter the least; because the air which interposes between the eye and the object seen, envelopes, in some measure, that object. If the air, which interposes, be in great quantity, the object seen will be strongly tinged with the colour of that air; but if the air be thin, then the view of that object, and its colour, will be very little obstructed.