Occasionally, and, indeed, in most good etchings or wood-cuts, the attention is still more perfectly confined; and there, as the principal feature cannot be so perfectly finished as in a drawing, the surrounding objects are indefinite exactly in proportion, ending frequently in mere spirited shade. And this is the reason that what most people would call a sketchy wood-cut, is far more agreeable to a good eye than the most laboured details, because, in fact, that which is most sketchy is most natural, and has more of the properties of a finished picture. Hence we see that the attention, in all good paintings and engravings, is distributed in a very limited degree, and chiefly concentrated upon one leading feature. Recurring, therefore, to our first principles, we find that when such concentration takes place, the limit of vision is faint, and undefined. All objects near the limit are so excessively indistinct, that a line cutting slightly upon them will not be felt. Accordingly, the artist generally cuts off an extremely small portion of the curve of his ellipse, A B, Fig. ﾆ, and including the whole of the other axis, encloses his whole figure between the right lines of a rectangle, whose proportion of sides, of course, indicates pretty nearly the length of the original axes, and, therefore, the whole form of the ellipse. He cuts off part of either axis, which he chooses, but very seldom curtails both. Of the included angles, B c, C D, &c., we shall speak presently. Now we have gone through the whole of this argument merely to prove what some might be inclined to dispute,-that the edge, or frame, of the picture, though rectangular, is, bona fide, the representative of the natural limit of sight; it is not an arbitrary enclosure of a certain number of touches, or a certain quantity of colour, within four right lines; nor is it to be extended or diminished as the artist wishes to include more or fewer objects; it is as clearly representative of a fixed natural line as any part of the design itself; and its size and form are, therefore, regulated by laws of perspective as distinct and as inviolable.
