The Handbook
Epictetus
Epictetus. The Discourses of Epictetus, with the Encheridion and Fragments. Long, George, translator. London: George Bell and Sons, 1887.
In walking about as you take care not to step on a nail or to sprain your foot, so take care not to damage your own ruling faculty: and if we observe this rule in every act, we shall undertake the act with more security.