[vacri]

That's a very good way of putting it.

One thing people don't realise is that depression screws with your perception of the value of things, maybe a little, maybe a lot. Trying to logically balance things like a mathematical equation is not a useful way of looking at things when discussing depression.

[InclinedPlane]

The major characteristic of severe clinical depression is that it takes away enjoyment from all manner of activities that used to be enjoyable. People who haven't experienced it or who have never been close to someone in the depths of depression are unlikely to be able to comprehend it.