These should all be studied. At the opposite of light are the shadows and shades. In art one not only has to know and understand what he is representing but also how to represent it. With the use of shades and shadows, different moods or atmosphere may be created and drama may be infused in the illustration. In impressionism it is the light effect as seen that is painted and not the head knowledge of the subject.
Illustration is a credible representation of life .
The illustrator also plays the role of the lighting director. The comics illustrator must learn how to draw the structures of things, real and imagined from the tiniest amoeba to the most gigantic creatures, existent or not. And, of course, the anatomy of man, the masterpiece of God's creation. This includes all the varying expressions and attitudes of man, the similarities and differences of the genders , the races , in motion or static , viewed from all angles , the clothed or unclothed , in all of man's poses . Knowing what to do is just one half of the deal.