The Pre-Raphaelites, therefore, may appeal to high authority for the cardinal doctrine of their creed; and whatever be their errors in judgment or in taste, they have inaugurated a revolution which will release art from its fetters, and give it a freer and a nobler aim. Nature is too grand in her minuteness, and too beautiful in her humility, to be overlooked in the poetry of art. If her tenderest and most delicate forms are worthy of admiration, she will demand from the artist his highest powers of design. If the living organizations of the teeming earth, upon which we hourly tread, are matchless in structure, and fascinating in colour, the palette of the painter must surrender to them its choicest tints. In the foreground of the highest art, the snail-shell may inoffensively creep from beneath the withered leaf or the living blade; the harebell and the violet may claim a place in the sylvan dell; the moss may display its tiny frond, the gnarled oak or the twisted pine may demand the recognition of the botanist, while the castle wall rises in grandeur behind them, and the gigantic cliffs or the lofty mountain range terminate the scene. If these views are sound, the man of taste will no longer endure slovenliness in art. He will demand truth as well as beauty in the landscape; and that painter may change his profession who cannot impress geology upon his rocks, and botany upon his plants and trees, or who refuses to display, upon his summer or his autumn tablet, the green crop as well as the growing and the gathered harvest. Thus enlarged in its powers and elevated in its purposes, the art of painting will be invested with a new character, demanding from its votaries higher skill and more extended knowledge. In former times, the minute and accurate delineation of nature was a task almost impossible, requiring an amount of toil which could hardly be repaid even when slightly performed; but science has now furnished art with the most perfect means of arresting, in their most delicate forms, every object, however minute, that can enter into the composition of a picture. These means are the arts of photography and stereoscopic re-combination, when rightly directed, and it is the object of the present chapter to shew how the artist may best avail himself of their valuable and indispensable aid.