>Let's take a trivial example. Person A is depressed because he is unhappy that he doesn't make enough money to travel and buy nice cars. Now take all the peopl

>Let's take a trivial example. Person A is depressed because he is unhappy that he doesn't make enough money to travel and buy nice cars. Now take all the people who are unhappy that they cannot afford to travel and buy nice cars. Most will not be depressed - they will merely be unhappy about it. These two words are semantically the same in your context. Unhappy = depressed. Unless you can define something measurable, and if you did in the comment above I can't find it. I suspect there is something measurable, but I don't see very much attempt at discerning what that is. And without it, this conversation is pointless.