SENSATION
We can best understand the problems of sensation and perception if we first think of the existence of two great worlds—the world of physical nature without and the world of mind within. On the one hand is our material environment, the things we see and hear and touch and taste and handle; and on the other hand our consciousness, the means by which we come to know this outer world and adjust ourselves to it. These two worlds seem in a sense to belong to and require each other. For what would be the meaning or use of the physical world with no mind to know or use it; and what would be the use of a mind with nothing to be known or thought about?
