
Fig. IO-I. Drawing by student
Elizabeth Arnold.
Light logic. Light falls on objects
and (logically) results in the four
aspects of light/shadow:
1. Highlight: The brightest light,
where light from the source falls
most directly on the object.
2. Cast shadow: The darkest shadow,
caused by the object's blocking of
light from the source.
3. Reflected light: A dim light,
bounced back onto the object by
light falling on surfaces around the
object.
4. Crest shadow: A shadow that lies
on the crest of a rounded form,
between the highlight and the
reflected light. Crest shadows and
reflected lights are difficult to see
at first, but are the key to "round-
ing up" forms for the illusion of
3-D on the flat paper.
N
ow that you have gained experience with the first three
perceptual skills of drawing—the perception of edges,
spaces, and relationships—you are ready to put them together
with the fourth skill, the perception of lights and shadows. After
the mental stretch and effort of sighting relationships, you will
find that drawing lights and shadows is especially joyful. This is
the skill most desired by drawing students. It enables them to
make things look three-dimensional through the use of a tech-
nique students often call "shading," but which in art terminology
is called "light logic."
This term means just what it says: Light falling on forms cre-
ates lights and shadows in a logical way. Look for a moment at
Henry Fuseli's self-portrait (Figure 10-2). Clearly, there is a
source of light, perhaps from a lamp. This light strikes the side of
the head nearest the light source (the side on your left, as Fuseli
faces you). Shadows are logically formed where the light is
blocked, for example, by the nose. We constantly use this R-mode
visual information in our everyday perceptions because it enables
us to know the three-dimensional shapes of objects we see
around us. But, like much R-mode processing, seeing lights and
shadows remains below the conscious level; we use the percep-
tions without "knowing" what we see.
Learning to draw requires learning consciously to see lights
and shadows and to draw them with all their inherent logic. This
is new learning for most students, just as learning to see complex
edges, negative spaces, and the relationships of angles and pro-
portions are newly acquired skills.
Seeing values
Light logic also requires that you learn to see differences in tones
of light and dark. These tonal differences are called "values."
Pale, light tones are called "high" in value, dark tones "low" in
value. A complete value scale goes from pure white to pure black
with literally thousands of minute gradations between the two
extremes of the scale. An abbreviated scale with twelve tones in
evenly graduated steps between light and dark is shown in Figure
194
THE NEW DRAWING ON THE RIGHT SIDE OF THE BRAIN