Although much has been said about the theoretical and abstract side of painting, and the importance of the æsthetic elements in art have been insisted upon, it is not to be supposed for a moment that painting does not deal with actual things. All painting which is not purely conventional must deal with and represent nature and natural facts. These are the body of the picture; the æsthetic elements are the heart of it. I believe that it is important that you should know that there is that side to painting, and should have some insight into it; that you should see that there is something else to think of than the imitation of natural objects. I would have you think more nobly of painting than to believe that "the greatest imitation is the greatest art." Beneath the imitation of the obvious facts of nature are the deeper facts and truths, and in and through these may you express those qualities of intellectual creation by means of which only, painting is not a craft, but an art.
But for all that, painting does, and always must, deal with those obvious facts; and however much you may give your mind to the problems of composition and color, you must base it on a foundation of ability to represent what you see. Represent well the external objects, and you are in a position to interpret the spirit of them. For as nature only manifests her inner spirit through her outward forms and facts, you must be able to paint these well before you can do anything else.
The intellectual action which perceives and constructs is the art, the skill which represents and reproduces is the science, of painting.
Painting is the art of expression in color. The fact of color rather than form is the fundamental characteristic of it. The use of pigment rather than other materials is implied in its name. Therefore the science of painting deals with the materials with which to produce on canvas all manner of visible color combinations; and those processes of manipulation which make possible the representation of all the facts of color and light, of substance and texture, through which nature manifests herself.
It is not enough to have the pigment, nor even that it should get itself onto the canvas. Different characteristics call for different management of paint. Luminosity of light and sombreness of shadow will not be expressed by the same color, put on in the same way. Different forms and surfaces and objects demand different treatment. The science of painting must deal with all these.