When one asks, "What is the heart? Where is the heart?" the answer usually is that the heart is in the breast. This is true; there is a nerve center in the breast of man which is so sensitive to our feelings that it is always regarded as the heart. When a person feels a great joy it is in that center that he feels something lighting up, and through the lighting up of that center his whole being seems light. He feels as if he were flying. And again, if depression or despair has come into his life this has an effect upon that center. A man feels his throat choked and his breath is laden as with a heavy load.