A Treatise on Painting/Chapter 315

Chap. CCCXV.Why Objects are less distinguished in proportion as they are farther removed from the Eye.

This happens because the smallest parts are lost first; the second, in point of size, are also lost at a somewhat greater distance, and so on successively; the parts by degrees melting away, the perception of the object is diminished; and at last all the parts, and the whole, are entirely lost to the sight[1]. Colours also disappear on account of the density of the air interposed between the eye and the object.

  1. See chap. cxvi. cxxi. cccv.