Place in the book. "The open door": the freedom to live by one's own nature, with death always at hand as an effortless exit. The discipline of action, with a secondary of desire.
The open door. Live here as you would if you had "gone out"; and if they will not let you — "EXERCISEdepart from life too, yet as one suffering no evil": death is no evil but an exit κατὰ φύσιν. The famous image of Epictetus (Disc. 1.25.18): "The room is smoky, and I leave" (καπνὸς καὶ ἀπέρχομαι) — the room fills with smoke, the door is open, so go out; but while the "smoke" is bearable, stay at your post.
Freedom. So long as nothing of the kind drives me out — "DOGMAI remain free, and no one will hinder me from doing what I will." Freedom lies not in circumstances but in the inalienability of the will: the external can kill me but cannot compel me.
What I will. "And I will what accords with TERMthe nature of a rational and TERMsocial being" (DOGMAto live according to nature). Freedom is not caprice: my θέλω is already determined by my rational-social nature. The door stands open without terror precisely because, even out of life, I lose nothing essential — my agreement with nature.
Discipline and parallels. The principal discipline is action (living by one's nature, the freedom of the will); the secondary is desire (death without evil, the open door). Parallels: Epictetus Disc. 1.25.18; 4.10; Med. 2.11 (one may depart now); 03-05 (the soldier at his post, awaiting the "recall-signal").