The reading was followed by the exposition (_enarratio_), grammatical, historical, philosophical, scientific, artistic, or literary. The master would tell his class the substance of the passage, and require them to turn verse into prose.[377] Books were not always forthcoming, and then dictation (practised also for its own sake) would be resorted to. At this time it was, perhaps, less common than in Horace’s day[378] owing to the multiplication of books. Learning by heart and writing exercises (_sententiae_, _chriae_) such as were practised in the rhetor’s school were among the obvious methods employed. Philology, of course, was in its infancy. It was based on Varro who had propounded such theories as ‘testamentum a testatione mentis’, ‘lucus a non lucendo’. There were two tendencies: that of the Romanists, who wished to derive everything from the Italian languages, and that of the Hellenists, who sought to prove that the origin of all words was Greek. There were also the ‘Anomalists’, who believed in the principle of change, and, like Horace, referred everything to custom, the controller and corrupter of words, and the ‘Analogists’, who believed in the principle of immobility, and proposed to subjugate custom to a fixed law of reason which operated by analogy.[379] How much in the dark even the best and soberest of grammarians were on the subject may be judged from Servius’s commentary on Vergil: on _Georg._ i. 17 ‘Maenala, mons Arcadiae, dictus ἀπὸ τῶν μήλων, id est ab ovibus’; on _Georg._ i. 57 ‘Sabaei populi ... dicti Sabaei ἀπὸ τοῦ σέβεσθαι’; on _Aen._ i. 17 ‘“thensa”[380] autem cum aspiratione scribitur ἀπὸ τοῦ θείου’.