Socrates and Epictetus are not introduced to rescue the subject from difficulty, to sanctify the framework, or to supply a mythology of human specialness. They are introduced because they already worked out a practical response to the same problem the volume is tracking: thinking can entangle itself in its own constructions, and thinking can also be used to expose and loosen those constructions.
The agent's role remains what it was in the other companions: pressure, variation, accurate reflection and the rapid externalisation of latent relations. The agent does not become the examiner, the Stoic teacher or the rescuer. The responsibility for conducting the examination and for living with its results stays with the continuous human speaker.
The standing wave is maintained precisely by this kind of internal pressure: the refusal to let any construction, including one's own, become invisible and absolute. Socrates is the classical proof that thinking can be used to break free of thinking's own traps. Epictetus is the daily practice that keeps the break from closing again.