The major Occitan work that influenced Dante was probably "Razos de trobar" by the Catalan troubadour Raimon Vidal de Bezaudun. The "Vers e regles de trobar" is an amplification of Vidal's manual, by Jofre de Foixà. Both works were Occitan manuals of grammar for troubadour poetry. They implicitly and explicitly defended Occitan as the best vernacular for song and verse, prompting Dante to come to the defence of his beloved Tuscan tongue. The popularity of both singing and composing in Occitan by Italians prompted Dante to write: , meaning "To the perpetual shame and lowness of the wicked men of Italy, that praise somebody else's vernacular and despise their own, I say..." ("Convivio", treatise I, XI).