Philosophy, in the ancient Graeco-Roman world, and in various other cultures too, was typically thought of as, among other things, bearing on how to live. Questions of how to live may now be considered by some as merely one optional specialism among others, but Derek Parfit for one, we shall see, rightly treats implications for how to live as flowing naturally from metaphysical theories. In the hope of showing something about the ancient Graeco-Roman tradition as a whole, I shall speak of things that I and others have said before,1 but I will highlight certain aspects of how the various groups or individuals related their philosophy to their lives. I shall start with the ancient Stoics as providing a clear case, then move on more briefly to their rivals, the Epicureans, and finally, more briefly again, to consider their predecessors and successors in other ancient schools and periods. This will not be a survey of the main central doctrines, although that is also something useful to attempt. But it will involve a selection of important ideas to illustrate their application to how to live.