Aristotle's Definition of Tragedy

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Philoctetes

κάθαρσις / purification

The catharsis or purification of painful or fatal acts involves a demonstration that those acts were done under circumstances (forced or performed in ignorance) which make the doer of those acts less than fully responsible for them. This demonstration involves a lightning flash of regret when the doer discovers his or her fatal mistake. Their purgation also involves considerable suffering and formal acts of contrition. Under these circumstances, the deeds are not written into the character of the doer, and his or her blood remains unpolluted.