The biographical information for the grammarian ‘Sergius’ is very unclear, if not non-existent. Under this name, about which there are legitimate doubts that it could be a variation of Servius (Keil, LII; Holtz, 227; Stock, 420), are transmitted some texts counted among the exegetical texts of Donatus that began to appear just after he first published his Artes, found their highest expression in the works of Servius, and finally established Donatus as an auctor and a model of grammatical praxis. Then, a whole series of commentaries and treatises on Donatus’ entire oeuvre or parts thereof (Ars minor; Ars maior I, II, III) characterises the grammatical panorama of Late Antiquity, and significantly influences the grammatical writings of the High Middle Ages (Law; Munzi 2007). Tradition attributes a handful of such texts to one ‘Sergius’ (Kaster, 429-30), which have been incorporated into the Grammatici Latini corpus: the De littera, de syllaba, de pedibus, de accentibus, de distinctione (GL IV, 475-485); the Explanationes in Donatum (GL IV, 486-565; doubts remain about their author and on the unity of the work: for a synthesis of these questions see De Paolis, 173-176); the so-called Sergius Bobiensis (GL VII, 537-539; Munzi 1993). For a long time, Cassiodorus was thought to be the writer of the Commentarium de oratione et de octo partibus orationis artis secundae Donati. The Benedictine scholar Garet first published it – a commentary to Maior II -  among Cassiodorus’ writings in 1679, and it was reprinted, still as the senator’s work, in the Patrologia Latina; the most recent editor, Stock, strongly attributed it to our not well known grammarian (following a line of thinking that started from reservations concerning authorship expressed by Keil and Manitius; see also Löfstedt and Law). The texts as a whole, however, cannot be attributed to a single author, but are an overlaying of material from Servius and Donatus, together with other treatises from the 5th century, like Pompeius and Cledonius, which in their entirety come from a Servius plenior, which was subjected, throughout the course of the tradition, to abbreviations and modifications (Jeep). The explicit citations of a source called ‘Sergius’, referring at once to De littera and the Commentarium, are found in later works from between the 7th and 9th centuries, both among the so-called ‘elementary grammars’ of the British Isles (especially the Ars Bernensis; Law 1982, 53-80), and among the texts of the ‘exegetic grammars’ (Ars Ambrosiana: Law 1982, 81-97). This discovery seems to offer a small amount of support for the more plausible hypothesis about the existence of the grammarian himself, and that the De littera and Commentarium may derive from a single writer (Stock, 409-410; Munzi 2005, 227, 231; but also consider the reservations of La Bua). Then, the earliest use of parts of the Commentarium by Isidore of Seville in the Etymologiae allows us to create a time frame, even if it is a large one (between Servius and Isidore), in which at least this text is connected to the name Sergius (Stock 22-23; more cautiously in this direction, Munzi 2005, 231). Some evidence, however feeble, on the figure of ‘Sergius’ can be deduced from the text of the Commentarium: the editor Stock, having examined the work’s auctores and grammatical sources and its style, suggested that it was composed in Campania in the first half of the 5th century. The Christian colouring of the language and, in particular, one citation of Paulinus of Nola, indicates a context typical to the early 400s, when literature and technical writing were characterised by a sort of linguistic and culture mixture and osmosis. This dating to the early 5th century is shared by Munzi 2005, although he does not consider the work’s presumed Christian features to be cogent or significant. [A. Di Stefano – tr. C. Belanger]