Seeing that an ideal in landscape is impossible, the landscape painter cannot improve upon nature. In the case of the human figure the painter may improve upon experience by collecting excellencies from different models and putting them into one form, thus creating what would be universally regarded as ideal physical beauty; and he may give to this form an expression of spiritual nobility which is also beyond experience because it would imply the absence of inferior qualities inseparable from man in nature. Thus to the physical, he adds intellectual beauty. Such a perfect form may be said to be an improvement upon nature, for it is not only beyond experience, but is nature purified. But the landscape painter cannot improve upon the signs which nature provides. He may vary the parts of a tree as he will, but it would never be recognized as beyond possible experience unless it were a monstrosity.[61] And even if he could improve upon experience with his signs, this would help him but little, for the beauty of a landscape depends upon the relation of the signs to each other, and not upon the beauty of the separate signs which vary in every work with the character of the design. In colour also the painter cannot apply to his landscape an appropriate harmony which the sun is incapable of giving. From all this it follows that the æsthetic value of a landscape depends entirely upon its correspondence with nature. A good landscape must necessarily be invented, because it is impossible to reproduce the particular beauty of a natural scene.[62] This beauty is due to a relation of parts of the view, infinite in number, to each other, but what this relation is cannot be determined by the observer. Further, whatever be the relation, the continuous changing light and atmospheric effects bring about a constant variation in the character of the beauty. It is possible for an actual view to suggest to the artist a scheme for a beautiful landscape, but in this the precise relation of the parts would have to be invented by the painter and fixed by experiment. The principal features from a natural view may be taken out, but not those which together bring about the beauty. There is no great landscape in existence which was painted for the purpose of representing a particular view. There have of course been scenes painted to order, even by notable artists, but these only serve the purpose of record, or as mementoes. The great view of The Hague, painted by Van Goyen under instructions from the syndics of the town, is the feeblest of his works, and the many pictures of the kind executed by British and German artists of the eighteenth century have now only a topographical interest. Constable painted numerous scenes to order, and there are something like forty views of Salisbury Cathedral attributed to him, but only those in which he could apply his own invention are of considerable æsthetic value. A good artist rarely introduces into a painting even a small