Normal sadness is categorized as an emotion, "the state of arousal defines by subjective states of feeling." The definition implies that emotion is immediate and reactive feeling that would be considered temporary. Depression is categorized as a moody, "a pervasive and sustained emotional response that can color perception." The definition implies that depression is long-lasting and how a person views the world, which effects one's feelings. Therefore one of the main difference between normal sadness and depression is the duration of time. Unlike normal sadness, the depression mood does not improve, regardless of activities or events that usually causes happiness or excitement. Even simple activities and jobs are difficult for someone that is depressed to thoroughly function. However, a person who is undergoing normal sadness is still able to function regularly at work or at a social event. Depression consists of four different symptoms; emotional, cognitive, somatic, and behaviroal. Cognitive contains a variety of signs such as slowed thinking, difficulty concentrating, guilt and worthiness, grandiosity, suicidal thoughts, and Beck's Depressive Triad. Somatic