In terms of productivity and functioning on social, economic and personal scales, depression is the most common and costly health problem in North America (Beutler et. all, 212). No one escapes the ups and downs of life. People suffer disappointments, inconveniences and losses that may upset them all the time. Some get depressed and some don't. In the case of a grievous loss it is natural to be depressed, but this fades with time and doesn't impair daily functioning for very long. "The models synthesized in clinical depression produce more extreme negative evaluations of self and more utterly hopeless pessimistic expectations of the future than the models synthesized in normal depressed moods" (Teasedale, 156).
             With cases of clinical depression negative feelings can snowball until they are too overwhelming for the person to function. "Signs of clinical depression can include sleep and appetite disturbances, fatigue, an inability to concentrate, memory problems, a decreased sex drive, excessive feelings of guilt, helplessness , and hopelessness, and sometimes thoughts of suicide" (Stevic-Rust & Maximin, 5). The nature of clinical depression is far more elusive, however, than a list of symptoms can indicate. Depression is comorbid with a host of conditions that may confuse the issue. Also, there are very few symptoms or causes that can be found in every case, few treatments that can work in every case, and the course of depression is never entirely predictable. "Depression is more aptly described as the common cold of emotional disorders or as the fever that indicates the presence of emotional and psychological distress" (Beutler, 254). The many facets of depression and theories which explain depression overlap and are often vague. Only by combining these observations and theories can a clearer picture of the nature of depression emerge.
             Depression co-oc...