In The Philosophy of Cognitive-Behavioural Therapy, Donald Robertson examines some of the allegories and metaphors used by the Stoics and other ancient philosophers to illustrate their ideas. For example, one common metepahor was that of athletic training. Another was military training. As Robertson explains, the "verbal principles of the Stoic are thought of as 'weapons' of the mind, which he uses to fight against emotional disturbance . . . The recollection of these weapons, the precepts of Stoicism, may possibly have been symbolized by the act of clenching the fist. For example,
The student as boxer, not fencer.
The fencer's weapon is picked up and put down again.
The boxer's is part of him. All he has to do it clench his fist. [Meditations, 12.9]"
Robertson points out that Stoic precepts weren't just quaint sayings or slogans, "more than just ideas tossed around in idle debate. These are the weapons used in the lifelong battle for happiness and mental health."