Be mindful not to injure your own character...

Just as you are careful, in walking about, not to step on a nail or to sprain your ankle, so be careful also not to hurt your governing principle. And if we observe this rule in every action, we shall be more secure in setting about it.

Epictetus is talking about prosoche or attention to ourselves, which we can call “Stoic mindfulness”. Socrates famously walked barefoot and, ironically, was friends with Simon the shoemaker, in whose shop he would sometimes discuss philosophy. Socrates’ friend and follower Antisthenes, and the Cynics who are were sometimes believed to have followed his example, were particularly known for going barefoot. In fact, there is a famous play about Socrates titled Barefoot in Athens, for this reason.

Diogenes Laertius quotes an Athenian satirist, Ameipsias, a contemporary of Socrates, who wrote of him: “Your sorry plight is an insult to the cobblers.” Likewise, Aristophanes wrote of Socrates in The Clouds: “You stalk along the streets, rolling your eyes, and endure, barefoot, many a hardship, and gaze up at us the clouds.”