Optical landscape, finally, is that which seeks to reproduce only the play of convergent or divergent, of reflected or broken light in nature. It is neither book-illustration nor views of places. It does not invite to the enjoyment of nature in the sense of the Sunday excursionist from big towns, or the summer tripper. It offers no scene with suggestion that we should live out our subjective moods there. The outlines, the plastic of the bodies, are a matter of indifference to it. Everything is merely a patch of colour to it; only an arena of dancing sunbeams. It wants to reproduce, as truly and fully as possible, the change and merging of lights and shades, the reciprocal influence of neighbouring and overlapping colours, the _crescendo_ of hues in the foreground and their fading away in the perspective. It systematically rates the intellectual and moral relations as foreign to its art. It is not enthusiastic for a particular season of the year or a certain architecture of cliffs and mountains. It knows nothing of the secret magic of water, heath, forest, or snow-plain. It gives light in scales, and in harmonised and dissonant chords, and will give nothing else. This landscape painting is an art of purely sensual preception, which may call pre-existent feelings and thoughts over the threshold of consciousness, but brings about no feelings and thoughts of itself. It is to be compared with the effect of the Æolian harp, which stimulates our hearing with melodious sound, but says nothing thematically differentiated to it. Debussy, latterly, consciously strives back to these origins of acoustic pleasure. The disciples of Turner in England and on the Continent enter in landscape on the same way back to a style of painting which, neglecting form, lays stress on the harmonies of light and colour. In practice, besides the three sharply outlined species of landscape painting, manifold transitions and mixed forms are, of course, also observable. If, perhaps, G. Poussin represents literary, Corot lyric, Turner, at the time the formation of his cataract began, optical landscape, in its theoretical purity, we see in Claude Lorrain a revelling in light and a poetic mood penetrate the mytho-heroic literary painting which he owes to his artistic training, and from which, in spite of higher flights, he could never entirely free himself; and Segantini is a good example of an originally lyrical landscape that is always more strongly inclining to the optical; for if at the beginning he loved to copy high mountains, at last he busied himself only with fixing the wonder of light in thin air on the mirroring ice and glacier snow.