In Greek and Latin, tropes () are generally defined as variations from a linguistic and stylistic norm (), either for stylistic purposes or for necessity. In this sense, they lie somewhere between a purely grammatical and a more rhetorical nature, since they may involve alterations of morphology, the semantic sphere of words, or syntactic peculiarities aimed at achieving a special expressive effect. Because of their ambiguous nature, tropes are in close proximity to what are commonly known as rhetorical figures (). From the Ancient times all the way to the Byzantine era, Greek grammarians wrote several treatises on tropes ( ). This book offers a critical edition of the extant texts on tropes transmitted by mediaeval codices, i.e. the ones attributed to grammarians such as Concordius, Georgius Choeroboscus, and the so-called Trypho I, Trypho II, Trypho III, Anonymus III and Anonymus IV. Each text is accompanied by an Italian translation. In the Introduction, besides a generic overview on the concept of trope (its genesis, its meaning(s), its development throughout centuries), an analysis of the contents and of the reciprocal relations between all these treatises is provided.