Two "with-"s. The verse (its text supplemented by editors: the angle brackets mark ‹δὲ›, ‹συ›, ‹χρεών› restored for the metre) is built on two verbs with the prefix συν- "together": μὴ συνεπιθρηνεῖν — "not to wail-along," μὴ συσφύζειν — "not to throb in time." σφύζειν is a medical term (of the beating pulse, of feverish palpitation): another's agitation is contagious, like a quickened heartbeat in a crowd. What is forbidden is not compassion but co-oscillation — the loss of one's own rhythm to another's.

Fellow-feeling without contagion. A fine line runs between κοινωνία and συμπάθεια in the bad sense. The Stoic is called to enter another's soul (6.53 — "get inside the speaker"), to help, to love (7.22) — but not to catch the affect: help presupposes firm footing, and whoever wails along with the wailer drowns beside him rather than pulling him out. The mechanism is the same as in 5.26: the sensation from the body is admitted, but the ruling part "adds nothing" of evaluative disturbance from itself — here the same, with others' passions as the source. Cf. the image of the rock in the surf (4.49): the waves break, the rock stands and stills the water that seethed around it. The discipline is assent.