That's the one thing I want to make clear about depression: It's got nothing at all to do with life. In the course of life, there is sadness and pain and sorrow, all of which, in their right time and season, are normal—unpleasant, but normal. Depression is in an altogether different zone because it involved a complete absence: absence of affect, absence of feeling, absence of response, absence of interest. The pain you feel in the course of a major clinical depression is an attempt on nature's part (nature, after all, abhors a vacuum) to fill up the empty space. But for all intents and purposes, the deeply depressed are just the walking, waking dead.
Source: Prozac Nation: Young and Depressed in America
Contributed by: Charles