Eudaimonism was the dominant theory in ancient Greek ethics. The name derives from the Greek word ‘eudaimonia’, which is often translated as ‘happiness’ but is sometimes translated as ‘flourishing.’ Many scholars in fact prefer the latter translation because they believe it better captures the concern of the ancient Greeks with the idea of living well. This preference suggests that a useful way of distinguishing between eudaimonism and egoism is to observe, when formulating their fundamental principles, the distinction between well-being and happiness that we drew in Chapter 2. Accordingly, the fundamental principle of eudaimonism is that the highest good for each person is his or her well-being; the fundamental principle of egoism remains, as before, that the highest good for a person is his or her happiness. Admittedly, this way of distinguishing between the two theories would be theoretically pointless if the determinants of how happy a person was were the same as the determinants of how high a level of well-being the person had achieved. Thus, in particular, when hedonism is the favored theory of well-being, this way of distinguishing between eudaimonism and egoism comes to nothing. It fails in this case to capture any real difference between them. For when hedonism is the favored theory of well-being, determinations of how happy a person is exactly match the determinations of how high a level of well-being a person has achieved.