For the Stoics, a person’s virtue does not depend, for example, on her sexual history. Instead, it depends on her excellence as a human being—on how well she performs the function for which humans were designed. In the same way that a “virtuous” (or excellent) hammer is one that performs well the function for which it was designed—namely, to drive nails—a virtuous individual is one who performs well the function for which humans were designed. To be virtuous, then, is to live as we were designed to live; it is to live, as Zeno put it, in accordance with nature.
