The opposite of hubris. The voice that says not yet, not now, hold. Odysseus does not have it on the Cyclops’s beach. He has it in spades by the time he comes home. [SPOILER: A suitor flicks a crust at his feet. Antinous throws a stool. A handmaiden mocks him. Eurycleia recognizes the scar on his thigh and he silences her with a hand at her throat — restraint enforced as much on himself as on her. He has built his whole homecoming out of small refusals to react. The man who once shouted his name at a Cyclops can now sit at his own hearth in rags and eat insults from men he is going to kill in three days. Sophrosyne is the muscle he failed to use at twenty and finally has at forty. It is what makes the slaughter possible.]
Sophrosyne
Self-restraint. The discipline to not do the thing you most want to do. Odysseus violates it on the Cyclops's beach. Years later he masters it in his own hall.