The Analysis of Beauty / Written with a view of fixing the fluctuating ideas of taste

by William Hogarth

And now let us have recourse to the experiments in life, for such examples as may explain the retiring power of each species; since, as has been before observed, they must be considered together with their proper forms, or else their properties cannot be well distinguished.

All the degrees of obliquity that planes, or flat surfaces are capable of moving into, have their appearances of recession perfected by the first species of retiring shades, which may evidently be seen by setting opposite a door, as it is opening outwards from the eye, and fronting one light.

But it will be proper to premise, that when it is quite shut, and flat or parallel to the eye and window, it will have only a penciling shade gradating upon it, and spreading all around from the middle, but which will not have the power of giving the idea of recession any way, as when it opens, and the lines run in perspective to a point; because the square figure or parallel lines of the door, do not correspond with such shade; but let a door be circular in the same situation, and all without side, or round about it, painted of any other colour, to make its figure more distinctly seen, and it will immediately appear concave like a bason, the shade continually retiring; because this circular species of shade would then be accompanied by its corresponding form, a circle[14].

[14] Note, if the light were to come in at a very little hole not far from the door, so as to make the gradation sudden and strong, like what may be made with a small candle held near a wall or a wainscot, the bason would appear the deeper for it.

Note also, that when planes are seen parallel to the eye in open day-light, they have scarce any round gradating or penciling shade at all, but appear merely as uniform prime tints, because the rays of light are equally diffused upon them. Nevertheless, give them but obliquity, they will more or less exhibit the retiring shade.

But to return; we observ'd that all the degrees of obliquity in the moving of planes or flat surfaces, have the appearances of their recession perfected to the eye by the first species of retiring shade. For example, then; when the door opens, and goes from its parallel situation with the eye, the shade last spoken of, may be observed to alter and change its round gradating appearance, into that of gradating one way only; as when a standing water takes a current upon the least power given it to descend.

Note, if the light should come in at the door-way, instead of the window, the gradation then would be reversed but still the effect of recession would be just the same, as this shade ever complies with the perspective lines.

In the next place, let us observe the ovolo, or quarter-round in a cornice, fronting the eye in like manner, by which may be seen an example of the second species; where, on its most projecting part, a line of light is seen, from whence these shades retire contrary ways, by which the curvature is understood.

And, perhaps, in the very same cornice may be seen an example of the third species, in that ornamental member called by the architects cyma recta, or talon, which indeed is no more than a larger sort of waving or ogee moulding; wherein, by the convex parts gently gliding into the concave, you may see four contrasted gradating shades, shewing so many varied recessions from the eye; by which we are made as sensible of its waving form as if we saw the profile out-line of some corner of it, where it is miter'd, as the joiners term it. Note, when these objects have a little gloss on them these appearances are most distinct.

Lastly, the serpentine shade may be seen (light and situation as before) by the help of the following figure, as thus; imagine the horn, figure 57, plate II, to be of so soft a nature, that with the fingers only, it might be pressed into any shape; then beginning gently from the middle of the dotted line, but pressing harder and harder all the way up the lesser end, by such pressure there would be as much concave above, as would remain convex below, which would bring it equal in variety or beauty to the ogee moulding; but after this, by giving the whole a twist, like figure 58, these shades must unavoidably change their appearances, and in some measure, twist about as the concave and convex parts are twisted, and consequently thereby add that variety, which of course will give this species of shade, as much the preference to the foregoing, as forms composed of serpentine lines have, to those composed only of the waving. See [Chapter IX] and [Chapter X].