The sketch is the germ of the picture. It contains the idea which may later become the finished work. In your sketches you gather effects and suggestions of possibilities, of all kinds. You do not work long over a sketch, nor do you work perfunctorily. You do not make it because you ought to, but because you see something in nature which charms you; or because you have found an idea you wish to make a note of.
Understand thoroughly the use and meaning of sketches, and you will get more good from the making of them. For your sketching is an important matter to your painting. You do not learn how to paint by sketching; but you can learn a great many things, and some of them you can learn no other way. A sketch is not a picture; neither is it a study. Each of these things has its special purpose and function, and its proper character.
A sketch is always a note of an idea--an idea seen or conceived. Everything is sacrificed in the sketch to the noting of that idea. One idea only, in one sketch; more ideas, more sketches.
There are two kinds of sketches: those made from nature to seize an effect of some sort; and those made to work out or express tersely some composition or scheme of color which you have in your mind. Both are of great use to the student as well as essential to the work of the artist.
[Illustration: =Sketch of a Hillside blocked in from Nature, First Suggestion of Composition, etc.=]
The first conception of a picture is always embodied in the form of a sketch, and the artist will make as many sketches as he thinks of changes in his original idea. It is in this form that he works out his picture problem. He is troubled here by nothing but the one thing he has in mind at this time. It may be an arrangement of line or of mass. He changes and rearranges it as he pleases, not troubling himself in the least with exactness of drawing, of modelling, of color, nor of anything but that one of composition. It may be a scheme of color, and here again the spots of pigment only vaguely resemble the things they will later represent; now they are only composition of color to the painter, and everything bends to that. When this has been decided on, has been successfully worked out, then it is time enough to think of other things. And think of other things he does, before he makes his picture; but not in this sketch; in another sketch or other sketches, each with its own problem, or in studies which will furnish more material to be used later; or in the picture itself, where the problem is the unity of the various ideas within the great whole in the completed painting.