Freud noted that a major drive for people is the reduction of tension and the major cause of tension was anxiety. He identified three types of anxiety: reality anxiety, neurotic anxiety, and moral anxiety. Reality anxiety is the most basic form of anxiety and is based on the ego. It is typically based on the fear of real and possible events (for example, being bit by a dog or falling off of a roof). Neurotic anxiety comes from an unconscious fear that the basic impulses of the id will take control of the person, leading to eventual punishment from expressing the id's desires. Moral anxiety comes from the superego. It appears in the form of a fear of violating values or moral codes, and appears as feelings like guilt or shame.