that is needed. But the difficulty is
not to carve quantities of leaves. Anybody can do that. The difficulty
is, never anywhere to have an _unnecessary_ leaf. Over the arch on the
right, you see there is a cluster of seven, with their short stalks
springing from a thick stem. Now, you could not turn one of those leaves
a hair's-breadth out of its place, nor thicken one of their stems, nor
alter the angle at which each slips over the next one, without spoiling
the whole as much as you would a piece of melody by missing a note. That
is disposition of masses. Again, in the group on the left, while the
placing of every leaf is just as skilful, they are made more interesting
yet by the lovely undulation of their surfaces, so that not one of them
is in equal light with another. And that is so in all good sculpture,
without exception. From the Elgin marbles down to the lightest tendril
that curls round a capital in the thirteenth century, every piece of
stone that has been touched by the hand of a master, becomes soft with
under-life, not resembling nature merely in skin-texture, nor in fibres
of leaf, or veins of flesh; but in the broad, tender, unspeakably subtle
undulation of its organic form.

167. Returning then to the question of our own practice, I believe that
all difficulties in method will vanish, if only you cultivate with care
enough the habit of accurate observation, and if you think only of
making your light and shade true, whether it be delicate or not. But
there are three divisions or degrees of truth to be sought for, in light
and shade, by three several modes of study, which I must ask you to
distinguish carefully.

I. When objects are lighted by the direct rays of the sun, or by direct
light entering from a window, one side of them is of course in light,
the other in shade, and the forms in the mass are exhibited
systematically by the force of the rays falling on it; (those having
most power of illumination which strike most vertically;) and note that
there is, therefore, to every solid curvature of surface, a necessarily
proportioned gradation of light, the gradation on a parabolic solid
being different from the gradation on an elliptical or spherical one.
Now, when your purpose is to represent and learn the anatomy, or
otherwise characteristic forms, of any object, it is best to place it in
this kind of direct light, and to draw it as it is seen when we look at
it in a direction at right angles to that