“Every week a doctor commits suicide in North America, and each one knew that depression is potentially treatable or self-limiting; insight goes faster in depression than in any other illness. Depression is psychological pain, and a severe depressive illness is arguably the most unpleasant disease in the Western world bar rabies. Samuel Johnson once said he’d suffer a limb to be amputated to recover his spirits. An old clergyman who had recovered from a severe depression later badly scalded his genitals, thighs, and abdomen. When asked which type of pain was worse, he said, ‘I would suffer the scalding a hundred times rather than have a depression again. Every night I pray to God to let me die before the depression returns. When I was scaled I prayed for relief and I was heard, but during the depression I lost my faith. There is no comparison between those two kinds of pain.'” 
A recent World Health Organization report predicts that depression will be the leading cause of disability and premature death in the industrial world by the year 2020. Without treatment, ten to fifteen percent of people suffering from severe Major Depressive Disorder commit suicide. With treatment, the majority of patients with this illness recover.