In itself colour has no virtues which are not governed by immutable laws. These are apart from the exercise of human faculties, the recognition of colour harmony being involuntary and entirely dependent upon the condition of the optic nerves. Thus there can be no meaning in colour apart from its application to form, and the extent to which it may be properly used in the representation of form is necessarily bound by our experience of nature. Other things being equal, the most perfect painting is that wherein there is a just balance between the colour and the form, that is to say, where the colour is not so vivid as to act upon the sense nerves before the general beauty of the work is appreciated, or so feeble or discordant that its want of natural truth is immediately presented to the mind, thus disturbing the impression of the design.
As with metrical form in poetry, the importance of colour in painting varies inversely with the character of the art. In the highest art, where ideals are dealt with, colour is of the least importance. A composition with ideal figures may be produced by drawing only, that is to say, by the use of a single tone in outline and shading. The addition of colour heightens the beauty of a composition of this kind, not so much because of the new sensorial harmony acquired, as for the reason that a painting in colours, corresponding better than a colourless drawing with our experience of nature, assists in defining the work and so reduces the fractional time necessary for the recognition of the general beauty of the design, which is a matter of importance. The comparatively small value of colour in the highest art is demonstrated by experience. If we were to choose from paintings known to us, those which general opinion regards as the very greatest works, we should unquestionably name the frescoes of Raphael and Michelangelo at the Vatican, and those of Correggio at Parma. These, with a few easel pictures of Raphael, and perhaps a dozen other pictures by various masters, are the only works of the painter's art to which the term "sublime" may be properly applied. As with the great epic poems, they are concerned entirely with ideals--with personages far above the level of life, rising to the spiritual domain--or with human beings as they would be if the highest conceptions of our imagination were possible of realization. When we recall these splendid legacies of genius to our minds, and ponder over the apparently limitless range of human vision which they evidence, it is the designs that absorb us, and not the colour--the forms and expression, and not the tints by which their definition is assisted. We do not usually analyse the impression we receive from these frescoes and pictures, but were we to do so, it would be borne in upon our minds that while a Raphael, a Michelangelo, or a Correggio, would be required to conceive and execute such stupendous designs, many thousands of unknown patient workers could be found to colour them efficiently. On the other hand if we remove the colour from the greatest landscape known to us, we find that most of the beauty of the work has disappeared, and that we have only a kind of skeleton left, for the beauty of such a picture rests very largely upon the aerial perspective, which is unobtainable without colour.