'Harmony, or a union of the different parts of a composition, depends upon the intermediate parts serving as a link or chain, either by conveying a sensation of the same colours with those in immediate contact, or by neutralising and breaking down the harsh asperities of the two extremes, and thus producing a connection or agreement. Breadth of effect is only to be produced by a great extent of light or shade pervading the picture. If an open daylight appearance is intended, such as we see in Cuyp, &c., it will be best produced by leaving out part of the middle tint, and allowing a greater spread of light and half-light; this will also give the darks the relative force which they possess in nature. If a breadth of shadow is required, such as we find in Rembrandt, &c., the picture ought to be made up of middle tint and half-dark. In the one treatment the dark ought to tell sharp and cutting, which is the characteristic of sturdy daylight; in the other, the light ought to appear powerful and brilliant, enveloped in masses of obscurity.'[12] Burnet, in his treatise, gives also examples of light and shade taken from the different masters. Light coming from the centre in a bright spot or focus, with darkness surrounding it, as in some of the Dutch pictures, where the light comes through a window, from a bright fire, a lamp, or a candle, the effect will be a splash of white upon a ground of dark grey and black; light coming from behind, where the effect is open air with the ground light and the dark work starting out. Light falling diagonally, almost equally divided, the light portion with the dark. Light striking into the picture, and falling upon the most prominent object, if in a room, the effect will be dark background; if outside, gloomy skies, as in autumn, winter, or storm effects. In landscape, this effect is apt to produce solemnity, weirdness, or grandeur; if in a room, the sombre yet rich depth of Rembrandt.[13] Light falling perpendicularly and horizontally, as in doorways and narrow passages, where the light comes in with difficulty. Light striking across the picture horizontally, as in sunrises, when the ground is in shadow.