Depression is something that doesn't just go away. It's just... there and you deal with it. It's like... malaria or something. Maybe it won't be cured, but you've got to take the medication you're prescribed, and you stay out of situations that are going to trigger it.
When I was sectioned for six months, that was one of the worst experiences of my life, not being able to go out and have freedom. Having experienced it, it's almost inexplicably awful.
Bipolar disorder, manic depression, depression, black dog, whatever you want to call it, is inherent in our society. It's a product of stress and in my case over-work.