The essence of good is a certain kind of reasoned choice

From The Daily Stoic by Ryan Holiday and Stephen Hanselman. 

The essence of good is a certain kind of reasoned choice; just as the essence of evil is another kind. What about externals, then? They are only the raw material for our reasoned choice, which finds its own good or evil in working with them. How will it find the good? Not by marveling at the material! For if judgments about the material are straight that makes our choices good, but if those judgments are twisted, our choices turn bad.

—EPICTETUS, DISCOURSES, 1.29.1–3