Literary criticism, the κρίσις ποιημάτων of Dionysius Thrax,[381] also played a part. The discussions in Macrobius represent an advanced stage of the sort of thing which was begun in the schools. Servius[382] discusses whether Vergil wrote ‘Scopulo infixit’ or ‘Scopulo inflixit’, and in Aulus Gellius we have questions raised as to Vergil’s use of _tris_ and _tres_, and Cicero’s use of _peccatu_ and _peccato_, _fretu_ and _freto_.[383] Again, Servius considers Probus’s doubts as to Vergil’s invocation to Jove as ‘hominum rerumque aeterna potestas’.[384] But, on the whole, such a critical attitude is rare. The commentator, and therefore the grammarian, is chiefly concerned with a mass of rather simple and diffuse exposition. The references are mainly to Lucretius, Horace, Pliny, Terence, Hesiod, and, most of all, to Homer. Grammatical notes, especially figures of speech, and geographical references are frequent and ample. Historical allusions, on the other hand, are rather slight. The critical faculty, then, was not very much alive. Indeed, one would hardly expect it to be from the general tone of the age, and from Servius’s own statement of the teacher’s duty. ‘In exponendis auctoribus haec consideranda sunt: poetae vita, titulus operis, qualitas carminis, scribentis intentio, numerus librorum, ordo librorum, explanatio.’[385] The grammarian thus moves on a fairly low plane. To him, ‘intentio Vergilii haec est, Homerum imitari, et Augustum laudare a parentibus’. The higher thought, the fundamental inspiration of the poem, ‘tantae molis erat Romanam condere gentem’, is omitted altogether. Of the text-books used, by far the most famous[386] was that of Donatus, who taught Jerome about the middle of the fourth century.[387] He was the model of succeeding writers and his name became a synonym for grammar. His work consisted of (1) an _ars minor_ for the elementary school, containing the parts of speech; (2) an _ars maior_, divided into three parts (_a_) ‘de voce, de littera, de syllaba, de pedibus, de tonis, de posituris’ (punctuation); (_b_) another treatment of the parts of speech; (_c_) ‘de barbarismo, de solecismo, de ceteris vitiis, de metaplasmo (grammatical irregularity), de schematibus (figures of speech), de tropis’.[388] We hear of a ‘Donatus provincialis’[389] which was used in Gaul, and it may well be that Jerome’s influence in the provinces served to spread the popularity of Donatus, especially when supported by the Roman tradition, though his work must have obtained a footing in the schools even on its own merits.