Aristotle, Poetics 1449b21-27
“We’ll talk later about mimesis in hexameter poetry and comedy. For now, let’s chat about tragedy, starting by considering the definition of its character based on what we have already said. So, tragedy is the imitation (mimesis) of a serious event that also has completion and scale, presented in language well-crafted for the genre of each section, performing the story rather than telling it, and offering cleansing (catharsis) of pity and fear through the exploration of these kinds of emotions.”
Περὶ μὲν οὖν τῆς ἐν ἑξαμέτροις μιμητικῆς καὶ περὶ κωμῳδίας ὕστερον ἐροῦμεν· περὶ δὲ τραγῳδίας λέγωμεν ἀναλαβόντες αὐτῆς ἐκ τῶν εἰρημένων τὸν γινόμενον ὅρον τῆς οὐσίας. ἔστιν οὖν τραγῳδία μίμησις πράξεως σπουδαίας καὶ τελείας μέγεθος ἐχούσης, ἡδυσμένῳ λόγῳ χωρὶς ἑκάστῳ τῶν εἰδῶν ἐν τοῖς μορίοις, δρώντων καὶ οὐ δι᾿ ἀπαγγελίας, δι᾿ ἐλέου καὶ φόβου περαίνουσα τὴν τῶν τοιούτων παθημάτων κάθαρσιν.