of the ray. This is the
ordinary academical way of studying form. Lionardo seldom practises any
other in his real work, though he directs many others in his treatise.

168. The great importance of anatomical knowledge to the painters of the
sixteenth century rendered this method of study very frequent with them;
it almost wholly regulated their schools of engraving, and has been the
most frequent system of drawing in art-schools since (to the very
inexpedient exclusion of others). When you study objects in this
way,--and it will indeed be well to do so often, though not
exclusively,--observe always one main principle. Divide the light from
the darkness frankly at first: all over the subject let there be no
doubt which is which. Separate them one from the other as they are
separated in the moon, or on the world itself, in day and night. Then
gradate your lights with the utmost subtilty possible to you; but let
your shadows alone, until near the termination of the drawing: then put
quickly into them what farther energy they need, thus gaining the
reflected lights out of their original flat gloom; but generally not
looking much for reflected lights. Nearly all young students (and too
many advanced masters) exaggerate them. It is good to see a drawing come
out of its ground like a vision of light only; the shadows lost, or
disregarded in the vague of space. In vulgar chiaroscuro the shades are
so full of reflection that they look as if some one had been walking
round the object with a candle, and the student, by that help, peering
into its crannies.

169. II. But, in the reality of nature, very few objects are seen in
this accurately lateral manner, or lighted by unconfused direct rays.
Some are all in shadow, some all in light, some near, and vigorously
defined; others dim and faint in aerial distance. The study of these
various effects and forces of light, which we may call aerial
chiaroscuro, is a far more subtle one than that of the rays exhibiting
organic form (which for distinction's sake we may call "formal"
chiaroscuro), since the degrees of light from the sun itself to the
blackness of night, are far beyond any literal imitation. In order to
produce a mental impression of the facts, two distinct methods may be
followed:--the first, to shade downwards from the lights, making
everything darker in due proportion, until the scale of our power being
ended, the mass of the picture is lost in shade. The second, to as