The present paper analyses one paradigmatic text of the “missionary genre”, that manifests in an exemplary manner its traits and characteristics: drifting through the multiple thematic waters that vocation imposes to his author he must face diverse activities, such as the study of strange languages, lexicography, contrastive reflection on the cultures to which he serves as a mediator and the translation of religious texts ; these are all tasks that in La Conversión en Piritú have their written expression.