I see depression as a state of one's mind on the outside world.
The real world is not perfect, so it's ok to have such states of mind that take us aside from the on-goings of the world.
I see such state as depression as a "something deep in me makes me see wrongs in the world, wrongs that it seems only I feel. I will understand those feelings of wrong. As the world is imperfect and composed of not a small number of wrongs, it is ok for me to see things as wrong".