The second is that leading principle which depends on sight, and which I call comparative proportion; because all objects appear great or small by comparison only, or as they have a reference to other objects with which they are liable to be compared. As this will be more clearly explained by an example, the vignette* at the beginning of the chapter presents two obelisks, of exactly the same size, yet by the figures placed near each, they appear to be of very different dimensions. The height of a man we know to be generally from five to six feet, but an obelisk may be from ten to a hundred feet high; we therefore compare the unknown with the known object, and immediately pronounce one of these obelisks to be twice the size of the other. Yet without some such scale to assist the eye, it would be equally difficult either in nature, or in a picture, to form a correct judgment concerning objects of uncertain dimensions.
*[Besides the obelisks in the vignette, are several other emblems relating to landscape gardening: the proportional compasses are often necessary to fix the exact comparative dimensions on paper, to reduce or enlarge the scale, and the flowing lines of ribbon or linen cloth are frequently necessary to mark the outline of a piece of water, when its effect is to be judged of at a distance; but, above all, the eye to observe and the hand to delineate, are always necessary, and will often supersede the use of every instrument; because the judicious artist must rather consider things as they appear than as they really exist, by which he may unite distant objects, and separate those in contact; his effects must be studied with the eye of the painter, and reduced to proper scale with the measurement of the land surveyor.]
