If a scene be taken from the middle distance only, as in many Barbizon works, the labour is much simplified because neither the close delineation of foliage, nor any considerable gradation of atmosphere is required, but then the beauty resulting from either of these two exercises is missing. It is equally impossible for such a scene to indicate growth and life, or the charm of a changing view. Some modern artists have a habit of blotting out the middle and far distance by the introduction of a thick atmosphere but this is an abuse of the art, because however true the aspect may be in the sense that a natural view is sometimes obscured by the atmosphere, the beauty of the scene as a whole is hidden, and the picture consists largely of an imitation of the mist, where an illusion of movement is impossible. The painter should imitate the more beautiful, and not the less beautiful aspects of nature. Jupiter has been sometimes painted as an incident in a picture, nearly wholly concealed by a cloud, but to exhibit a separate work of the god so concealed, would only be regarded as an excuse for avoiding exertion, however well the cloud may be painted; yet this would not be more reprehensible than to hide the greater part of a view by a dense atmosphere. With a clear atmosphere an illusion of opening distance may be secured with the far distance and the greater part of the middle distance unobservable, but in such a case a successful design is difficult to accomplish owing to the limited number of signs available. Many signs, as trees and houses, either darken or hide the view, while sunlight effects on unobstructed ground, sufficiently definite to be used as signs, could not be very numerous without appearing abnormal. The only really first-class method of producing a satisfactory near-ground illusion was invented by Hobbema in the later years of his life. This is to use skilfully placed trees and other signs through which paths wind, or appear to wind, and to throw in a strong sunlight from the back.[a] The light enables far more signs to be used in depth than would otherwise be possible, and so the eye has a comparatively long track to follow. That the remarkable beauty of the pictures of Hobbema composed in this way is almost entirely due to the illusion thus created, is readily seen when they are compared with some of his other works, very similar in all respects except that the light is thrown in from the front or the side. Before placing his light at the back, the artist tried the side plan in many pictures, and while this was a decided improvement upon his earlier efforts to secure depth of near-ground signs, it was naturally inferior to the latest scheme. Jacob Ruysdael adopted the plan of Hobbema in two or three works with great effect.[b] [a] See Plate 18. [b] For example, The Marsh, Hermitage.