hey
present, are never expressible by single black lines, or lines of simple
shadow. A crack must always have its complete system of light and shade,
however small its scale. It is in reality a little ravine, with a dark
or shady side, and light or sunny side, and, usually, shadow in the
bottom. This is one of the instances in which it may be as well to
understand the reason of the appearance; it is not often so in drawing,
for the aspects of things are so subtle and confused that they cannot in
general be explained; and in the endeavor to explain some, we are sure
to lose sight of others, while the natural overestimate of the
importance of those on which the attention is fixed causes us to
exaggerate them, so that merely scientific draughtsmen caricature a
third part of Nature, and miss two-thirds. The best scholar is he whose
eye is so keen as to see at once how the thing looks, and who need not
therefore trouble himself with any reasons why it looks so: but few
people have this acuteness of perception; and to those who are destitute
of it, a little pointing out of rule and reason will be a help,
especially when a master is not near them. I never allow my own pupils
to ask the reason of anything, because, as I watch their work, I can
always show them how the thing is, and what appearance they are missing
in it; but when a master is not by to direct the sight, science may,
here and there, be allowed to do so in his stead.

51. Generally, then, every solid illumined object--for instance, the
stone you are drawing--has a light side turned towards the light, a dark
side turned away from the light, and a shadow, which is cast on
something else (as by the stone on the paper it is set upon). You may
sometimes be placed so as to see only the light side and shadow,
sometimes only the dark side and shadow, and sometimes both or either
without the shadow; but in most positions solid objects will show all
the three, as the stone does here.

52. Hold up your hand with the edge of it towards you, as you sit now
with your side to the window, so that the flat of your hand is turned to
the window. You will see one side of your hand distinctly lighted, the
other distinctly in shade. Here are light side and dark side, with no
seen shadow; the shadow being detached, perhaps on the table, perhaps on
the other side of the room; you need not look for it at present.

53. Take a sheet of note-paper, and holding it edgewise, as you hold
you