Reasons.—Painting is something more than laying on paint. It implies a certain amount of knowledge of necessary preliminaries—technical matters which are not strictly painting, but without which good painting is impossible.

It is all well enough to put paint on canvas, but there must be a knowledge on which to base the where and the why of laying it on, as well as the knowledge of how to lay it on. If anything, the where and why are more important than the how. There are almost infinite methods and processes of getting the paint onto the surface. Every painter may select or invent his own way, and provided it accomplishes the main purpose—the bringing about of combinations of form, relative color and pitch, the expression of an idea—it is all right. But there are laws which govern the positions of the different spots of paint, and the reasons for placing them in certain relations. These laws are back of personal idiosyncrasy. They are a part of the laws which control all material things. The painter may no more go contrary to them in painting than he may go contrary to physical laws in any of the practical matters of life. If pigments are not used in accordance with the laws governing their chemical composition, they will not stand. If the laws of proportion are not observed in composition, the picture will not balance. The laws of color harmony are as mathematically fixed as the law of gravity. So, too, the relations of size, which give the impression of nearness or distance to objects, rest on the laws of optics. You have infinite scope for individual expression inside of those laws, but you cannot go outside of them.

Scientific Knowledge not Necessary.—It is not necessary that you should have any special knowledge of all these laws nor even of the application of them; but you must recognize their existence, and have some practical notions about them and their effect on your work.

You can of course carry the study as far as you are interested to go. The farther the better. The more you study them the more you will find them interesting, and the easier will it be for you to work freely within their limitations. But this is not the place for special study. There are books which treat particularly of these things, and you must go to them.

But a superficial consideration of these subjects cannot be left out of any book which would be really helpful to the student of painting. I can go into the theory of things only so far as to give you that amount of practical knowledge which is absolutely necessary to you as a painter. What I shall give is given only because it cannot be wisely left out, and the form of it as well as the substance and quantity are determined by the same reason.

As you hope to become a painter, then, do not neglect to study and think of this part of the book, not merely as a preliminary to the process of painting, but as containing matter which is continually essential to it—which is part and parcel of it.

Another reason for the careful reading of these chapters is that any discussion of the art of painting necessarily demands the use of words or phrases which must be understood. To speak of technical things presupposes the use of technical phrases, and without a knowledge of the words there can be no comprehension of the thought.