 The approach taken in this article follows Hadot’s (1998, 5) idea that for the ancients philosophy was a way of life, and that Marcus’ Meditations show us what it was like for an individual to try to live a Stoic life. However, rather than trying to cover all the themes in Marcus in this light—in addition to the topics discussed below, he talks about time, fate, death, the cycles of change in the cosmos—I focus on one basic question for Marcus’ project of living Stoically: what does a Stoic use to guide his own conduct? Addressing this basic question leads into discussion of the two virtues Marcus has the most to say about: justice and piety.