Rhetoric was the core of ancient education. The production of ‘good men skilled in speaking’ was not a literary affectation; it was a practical necessity in a world where public business was carried on orally. Rhetorical correctness became, therefore, the mark of the educated man; a writer who could not express himself properly was one who would not be taken seriously, like a modern scientist ignorant of mathematics. Lactantius and Arnobius were both professors of rhetoric; indeed, though neither mentions the other in his surviving works, Arnobius taught Lactantius. Both men knew that their intelligent contemporaries despised Christianity because it was crudely expressed: ‘The language is trivial and sordid,’ Arnobius’ opponents complained (Nat. 1.58.2); ‘They think nothing true except what is sweet to listen to,’ wrote Lactantius; ‘they do not therefore believe in the divine utterances because they lack adornment, and they do not trust those who interpret them because such people are generally ignorant’ (Inst. 5.1.17–18). The objection was not frivolous; it expressed a sense that Christianity was fundamentally incompatible with what was known about the way the world worked. The Christians were frankly stupid; stultitia, said their persecutors, had laid hold of them (so Galerius: Mort. 34.2; cf. Inst. 5.18.12). Lactantius and Arnobius confronted this judgment on their convictions in contrasting ways.