Catharsis

It's famous enough: 'Tragedy is, then, a representation of an action that is heroic and complete and of a certain magnitude—by means of language enriched with all kinds of ornament, each used separately in the different parts of the play: it represents men in action and does not use narrative, and through pity and terror it effects a katharsis of these and similar emotions.' [Aristotle, Poetics 1449b]

But what hasn't occurred to me before is the idea that Aristotle actually means what he says here: that the purpose of tragedy is to produce pitiless, fearless men; men who could fight in the Athenian army and navy without qualm or hesitation, who could kill without mercy. It could be that Aristotle's theory is that tragedy produces cold-eyed killers, and good thing too.