Chapter IV on simplicity: the painters accordingly divide theirs into

fore-ground, middle-ground, and distance or back-ground; which simple and distinct quantities _mass_ together that variety which entertains the eye; as the different parts of base, tenor, and treble, in a composition in music, entertain the ear.

Let these principles be reversed, or neglected, the the light and shade will appear as disagreeable as fig. [91 T p. II], whereas, was this to be a composition of lights and shades only, properly disposed, tho' ranged under no particular figures, it might still have the pleasing effect of a picture. And here, as it would be endless to enter upon the different effects of lights and shades on lucid and transparent bodies, we shall leave them to the reader's observation, and so conclude this chapter.