A jealous man can never be happy. (Epictetus)

That's a really interesting way to put it! Epictetus is suggesting that jealousy itself is the barrier to happiness. It's not necessarily that *not* being jealous guarantees happiness, but rather that the presence of jealousy actively prevents it. It makes you think about what we hold onto, doesn't it? Perhaps by letting go of that possessiveness, we open ourselves up to more peace.