We are limited by many things,
Talent , Creativity,
Procrastination and Experience,

But our primary obstacle is the limited range of light available to us.

Go outdoors on a bright sunny day. Look around. Find the lightest light. Find the darkest dark.

The lightest light might be the upward facing surface of a yellow leaf, gleaming in the sun.

The darkest dark might be the ground partly visible under the porch, which itself is in shadow.