We rely primarily on our eyes to understand form, and form is

revealed to us by light. When you pick up a three-dimensional

object with your eyes closed, feeling it with your hands, you

can learn some general information about the form, but no

real detail. If you open your eyes, the form is instantly much

clearer because of the way light is refl ected from the object,

revealing its shape. If you then rotate the object, you soon have

a complete grasp of its mass and volume, because you are able

to perceive it from all sides.