is 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.

* * * * *

Another requirement is rapidity of execution. I am not speaking of
figure-drawing. I can well understand why the model grows tired,
although the crude lay figure may not, and why the constant workings
over and again upon the figure subject, the mosaicin