The word for burning passion, enthusiasm, has a "god" hidden inside it. In Greek, en means "within" and theos means "god," and together they form entheos — "having a god within." In ancient Greece, when a poet or an oracle-bearing priest was seized by divine inspiration and fell into an ecstatic, otherworldly state, the Greeks called it enthousiasmos: "possession by a god, divine inspiration." Over the centuries the word shed its religious overtones and came to mean simply the warm, all-consuming "passion, zeal" we feel when we throw ourselves into something.