As to the value of the laws which govern the perfect composition, it is unquestionably true that a correct knowledge of these laws makes or unmakes the picture and establishes or ruins the rank of the painter. No matter how careful the drawing, how interesting the subject, how true the mass, how subtle the gradations of light and shade, how perfect the expression of the figures, or how transparent the atmosphere of a landscape, a want of this knowledge will defeat the result. On the other hand, a good composition--one that "carries," as the term is--one that can be seen across the room, if properly composed will instantly excite your interest, even if upon near inspection you are shocked by its crudities and faults. "I don't know what it is," says a painter, "but it's good all the same."
After your selection has been made, the next thing is to search for its centre of interest. When this is found it is equally important to weigh carefully the _quality_ of this centre of interest in order to determine whether, as has been said, the subject is worth painting at all. My own rule is to spend half the time I am devoting to my sketch in carefully weighing the subject in its every detail and expression.
Many men, I am aware, have endeavored to prove that there are eight or ten different forms of composition. My own experience and investigation are, of course, limited, but so far I have only been able to discover one, namely, the larger mass and the smaller mass: the larger mass dominating the centre of interest, which catches your eye instantly at first sight of a picture, and the smaller or less interesting object which next attracts your eye, and so relieves the vision and spares you the monotony of looking at a single object long and steadily, thus fatiguing the eye and dissipating the interest.
Having determined upon the _quality_ of the subject-matter and fixed its centre interest in pleasing relation to the whole, the next step is to confine yourself to all that _the eyes see at one glance_ and no more, or, in other words, that portion of the landscape which you could cut out with the scissors of your eye and paste upon your mind. That which you can see when your head is kept perfectly still, your eye looking straight before you, only seeing so high, so low, and so far to the right and left, without a strain. The great sweep of vision, a sweep covering a hundred subjects perhaps, is obtained by turning the eyes up or down or sideways. But to be true--that is, to see one picture at a time--the eye should be fixed like the lens of a camera, the limit of the picture being the range of the eye and no more. A departure from this rule not only confuses your perspective but crowds a number of points of interest into the square of your canvas, when there is really only _one_ centre point before you in nature; and this one point you must treat as does the electrician in a theatre who keeps the lime-light on the star of the play.