Chapter XVIII: Section I: (Tragedy) classifies characterization by types

(good rulers, bad rulers, etc.) and by the sophistic headings
for encomium. “Appropriateness of the traits of the tragic
personae consists in conformity (_decoro_) to age, emotion,
sex, country, profession” (folio 24, verso). In a word, it is
consistency. Chapter IX sums up what makes “una perfettissima
tragedia”; and the concluding chapter (X) exemplifies an ideal
tragic plot (_argomento_) by a novella of Boccaccio.