 The concept of eudaimonia, a key term in ancient Greek moral philosophy, is standardly translated as “happiness” or “flourishing” and occasionally as “well-being.” Each translation has its disadvantages. The trouble with “flourishing” is that animals and even plants can flourish but eudaimonia is possible only for rational beings. The trouble with “happiness” is that in ordinary conversation it connotes something subjectively determined. It is for me, not for you, to pronounce on whether I am happy. If I think I am happy then I am—it is not something I can be wrong about (barring advanced cases of self-deception). Contrast my being healthy or flourishing. Here we have no difficulty in recognizing that I might think I was healthy, either physically or psychologically, or think that I was flourishing but be wrong. In this respect, “flourishing” is a better translation than “happiness”. It is all too easy to be mistaken about whether one’s life is eudaimon (the adjective from eudaimonia) not simply because it is easy to deceive oneself, but because it is easy to have a mistaken conception of eudaimonia, or of what it is to live well as a human being, believing it to consist largely in physical pleasure or luxury for example.