A large number of the chapters in Aulus Gellius’ Noctes Atticae are dedicated to grammar, which was considered to be of primary importance among the ingenuae artes. In this sphere Gellius therefore had to be an authority, not an amateur, so as to establish himself in a position contrasting with that of scholastic grammar. The Roman ars grammatica provides, at least up to the time of Gellius, fairly clear glimpses of a double tradition: one trend is of a scholastic nature and is directed mainly at the parts of speech (partes orationis); the other is a more specialized type and turns its attention toward the question of correct language as based on several canons (natura, analogia, consuetudo, auctoritas). In Gellius we have ample evidence of this twofold tradition. In fact, we have (as also, though to a lesser degree, in Quintilian’ s Institutio Oratorio) a rather extensive compendium of ars grammatica, which can be reconstructed in its fundamental lines and organic structure and whose purpose it is possible to recognize, even if the variety of topics and logical disarray of the Noctes Atticae have always impeded our understanding of any systematic Gellian doctrine and have favored negative assessments of the author, who has generally been considered a dilettante in matters of language science. Though depending on multiple sources, Gellius seems, on the contrary, sufficiently original and independent in his judgments. In all likelihood his own originality and a certain coherence and freedom of thought are not unrelated to the archaizing movement of his time and to the cultured ambience of contemporary Rome. In linguistic analysis Gellius is a champion of a special rationality, which again avails itself of etymology, long since dispensed with by the traditional ars grammatica, and as a sophisticated scholar of language (he has even “cultivated” his own sources), Gellius places himself outside the scholastic grammatical tradition and proposes a form of linguistic inquiry that is predicated on various decision-making criteria, foremost among which is knowledge of the history of words from the most ancient authors to contemporary speech.