Depression being only episodic? I think not I'm afraid. Many times it is, but there are people with the disease whom never 'recover' in the real sense of the word and require essentially lifetime intervention with therapy, drugs or other treatment. It's a difficult thing to live with and I think part of the problem of understanding is those of us on the outside simply can't understand what it is to be depressed 'all the time', and not necessarily for any particular reason.