Depression can be both a sickness and a revelation of truth. One may be depressed due to chemical imbalances or more medically related issues, however when you look at life, it is rather grim. It's proven that intelligent people are more commonly depressed than those who are not, or vice versa, that depressed people are commonly more intelligent than those who are not. In any scenario, I believe that those who are understanding of reality and it's current state, tend to feel depressed as it is not in any-way, exactly positive. So many things about life are depressing, and although there is indeed a balance of both positivity and negativity, the balance in tipped. Even if one were to say that there is more positive than negative, which I disagree with.. it is quite apparent that our society focuses much more on that of which is negative than that of which is positive.