It was, at one time, common to believe that human emotions were created by some special organ in the body. The heart was thought to be the source of most worthy emotions, such as love, while other parts of the body were thought variously to be the source of other emotions, such as fear, hate, jealousy, anger, and the like.

The brain was correctly identified as the location of rational thought, but emotions were considered to be quite different, and separate from thought.

Except for the common figures of speech and popular images that still reflect these earlier theories, modern scientific study has pretty well established that emotion, like rational thought, is a process of the human brain, or mind.

Operations have been conducted on the brain in which various parts of the brain have been removed or isolated, resulting in a reduction of the individual's ability variously to think, and to feel emotion.