"A landscape is supposed to be viewed from the spot marked E; and that the spectator is desirous of representing on the plane of his paper a certain portion of the scene as seen by him fom this point. That portion constitutes his real picture. The distance of this picture,- or distance of the eye from the plane of the picture (which is the same thing), -means the distance intervening between the spectator's position, and that point on the ground directly in front of him, where the picture, which he is about to make, ought properly to commence. Upon the choice of a proper and judicious distance the beauty of his work will in a great measure depend. Suppose the landscape to be viewed from the point E, then that portion of the scene which the eye can easily take in, without moving the head, and without the slightest strain upon the optic nerve, will constitute the picture from that point. Now, under this condition the spectator will find that he does not distinctly see the ground immediately before him, but that he obtains a perfectly easy view of it only at some distance from his position at E. It is the space included between the point E (where he is placed), and the supposed point alluded to, and here marked S, that establishes the required distance of the picture, that is, the distance of the eye from the proposed picture. For instance, let S be that point on the ground immediately in front of the eye, and if through S a straight line be supposed to be drawn, perpendicular to the distance ES, this line will pass through and determine the foremost objects of the proposed picture, and therefore at this line the picture must commence."