Depression is a disorder of mood, so mysteriously painful and elusive in the way it becomes known to the self--to the mediating intellect--as to verge close to being beyond description. It thus remains nearly incomprehensible to those who have not experienced it in its extreme mode, although the gloom, "the blues" which people go through occasionally and associate with the general hassle of everyday existence are of such prevalence that they do give many individuals a hint of the illness in its catastrophic form.

William Styron