A Treatise on Painting/Chapter 116
Chap. CXVI.—What Parts of Objects disappear first by Distance.
Those parts which are of less magnitude will first vanish from the sight[1]. This happens, because the shape of small objects, at an equal distance, comes to the eye under a more acute angle than the large ones, and the perception of them is less, in proportion as they are less in magnitude. It follows then, that if the large objects, by being removed to a great distance, and consequently coming to the eye by a small angle, are almost lost to the sight, the small objects will entirely disappear.