Eudaimonia

Eudaimonia (εὐδαιμονία) is the word the Greeks used for happiness, but its make-up shows that it means something deeper and steadier than a passing feeling of pleasure. It joins eu (εὖ), 'well' or 'good', to daimōn (δαίμων), the indwelling spirit or guardian divinity — so that to be eudaimōn is, literally, to have a good spirit within, to be well-attended by one's daimon. For this reason it is often better rendered 'flourishing' or 'faring well' than 'happiness': it describes a life that is going well as a whole, not a momentary mood.

Eudaimonia is the agreed goal, the telos, of nearly all ancient ethics, however much the schools differed over its content. Aristotle argued in his Ethics that it is the highest human good, the one thing chosen always for its own sake and never for the sake of anything else, and that it consists in the activity of the soul in accordance with excellence over a complete life — not a state one possesses but an activity one performs.

For Plato and the tradition after him, true flourishing is inseparable from the good condition of the soul and ultimately from the knowledge of the Good; the just soul is the happy soul, even on the rack, and the tyrant, though he seem to prosper, is the most wretched of men. Flourishing, on this view, is not granted by fortune from without but grown from within, through the ordering of the soul — which is the work of philosophy.