In this episode of "Tu aqui tu lá com a história do teatro", the drama Frei Luís de Sousa, by Almeida Garrett, is analysed through the lens of textual criticism. Allied with theatre history this perspective help us to better understand this classic text of Portuguese dramaturgy. Professor João Dionísio, researcher at the Linguistics Centre of the University of Lisbon, is the guest speaker, with Professor Ana Isabel Vasconcelos, researcher at CET and lecturer at Universidade Aberta, as interlocutor.