Universal Impossibilities

I once read you can't fold a piece of paper more than seven times and, of course, proceeded to fold a piece of paper. The idea of impossibilities ranges from the obvious (walking on water) to the absurd (licking your elbow), and all feel comforting in some way by their absoluteness. But science is less slippery than emotions so when I read this by philosopher Arthur Schopenhauer I was less sure.

- 'It's difficult to find happiness within oneself, but it's impossible to find it anywhere else.' - Schopenhauer

At first, it reads like a common self-help trope. But when you mull it over it gets more interesting. The places and ways we look for happiness are so personal & contextual. Are we truly able to know what makes us happy unless we truly know ourselves? Schopenhauer was sure it's impossible. What do you think?