 First, the fabric of the eudaimonist approach to practical reasoning and life — inherited from the Greeks — begins to fray. For better or worse, on the Greek eudaimonist views (including here Plato, Aristotle, the Stoics, and Epicurus) our reasons for action arise from our interest in a happy life. If the reason-giving nature of others arises from a different source, as this reading of Aquinas suggests, then practical reason seems to have a duality of ultimate sources, with the complications that kind of duality brings.