Depression is Not a Destination

I came to a horrific realization lately. I'm dealing with depression (can't imagine why). But what is depression exactly? Is it a hopeless, relentless abyss? Is it a means to improve oneself? Is it useful in any way whatsoever? And most of all, how can it be overcome? I look at all of these questions, among others, in this podcast, and strangely find a source of joy embedded within depression itself, if its managed the appropriate way.