There are three areas in which the person who would be wise and good must be trained. The first has to do with desires and aversions- that a person may never miss the mark in desires nor fall into what repels them. The second has to do with impulses to act and not to act- and more broadly, with duty- that a person may act deliberately for good reasons and not carelessly. The third has to do with freedom from deception and composure and the whole area of judgment, the assent our mind gives to its perceptions. Of these areas, the chief and most urgent is the first which has to do with passions, for strong emotions arise only when we fail in our desires and aversions.
—Epictetus, Discourses, 3.2.1-3a