Humanist literary historians treated Aristotle’s ‘Poetics’ in a distinctive way: as a historical source. How had the Greek tragedy arisen, what was its relation to the comedy, and how was it performed? They approached Aristotle’s scanty and confusing words with a repertoire of methods: bold inference and exegesis, textual criticism, and above all comparison with Roman texts. These discussions were deeply relevant to the rise of the opera around 1600. Angelo Poliziano, Francesco Robortello, Piero Vettori, and Francesco Patrizi da Cherso are examined.