In the wake of Kate Spade and Anthony Bourdain's suicides, English professor Jennifer Finney Boylan attempts to distinguish between clinical depression and situational sadness:
Depression can be a kind of blindness that blacks out everything but the worst. An artist — or anyone — who is suffering from that blindness isn’t someone who is seeing a reality the rest of us cannot face. Most of the time, that person is just an innocent soul who has been seduced by a voice that is separating her from the truth.
Sadness, on the other hand, is a natural and reasonable reaction to the miseries of the world, some of them personal, some universal. There’s nothing unhealthy about sadness, and if certain things about the world at present fail to make you miserable, then you’re simply not paying attention…. The problem is that it can be hard to tell the two apart.
I'm personally aware of at least one psychiatrist who would take issue with Boylan's assessment that depression is a "blindness." It could be seen as a kind of heightened awareness — a deep, nagging acknowledgment that the world is a place full of needless despair; plus, death faces and haunts us all. Indeed, depression can be a catalyst for insight. Some historians, for instance, have argued that absent Abraham Lincoln's chronic depression, he would have been a much lesser president. His tremendous empathy, born of deep depressions, was key to his leadership.
I gave away my own experienced distinction betwixt true depression (which, in my case, has happily leveled out to mere dysthymia) and ordinary sadness in my opening sentence. If your sadness is accompanied by trouble sleeping (or trouble awakening), a loss of appetite, an avoidance of hobbies and difficulty in concentration, you are likely clinically depressed and in need of medication. If, on the other hand, you experience sadness because of money or job or relationship problems, well, who wouldn't? Your condition is situational. But please, don't take my word for it. If you're uncertain as to which is which in your life, see a shrink.
The oppressive weight of depression once suffered from an insufficiency of description — until, that is, novelist William Styron wrote of his own bouts of depression, in Darkness Visible: A Memoir of Madness. "I’d feel the horror, like some poisonous fogbank, roll in upon my mind." His is a tour de force in self-examination. I strongly recommend it. If you're depressed it offers sympathetic recognition and hope. It could save your life.