Chapter 15 begins by presenting the idea that term mental illness is hard to define. Mental illness is hard to define because there is no clear definition, instead psychologists and psychiatrists have developed criteria to explain what mental illness is. The 5 main criteria that define the term mental illness are: statistical rarity, subjective distress, impairment, societal disapproval, and biological dysfunction. I thought it was very interesting that anxiety is among the most common mental disorders today. The biggest information that struck me while reading the chapter was mood disorders and suicide. In this section of the chapter it said that 20% of us will experience a mood disorder, and depression has reached about 16% of people. Because of such a high percentage, they have named depression the "common cold" of psychological disorders. While reading this I thought about the fact that many people have felt depressed in their lives, but not many of us have felt the great depths of suffering that many people have experienced. The idea of suicide is a very hard one for me to understand, because of the sadness that must be experienced within the person committing.