What would the ancients have made of Charlie Hebdo? The First Amendment tolerates the expression of opinions, however offensive, but not behaviour that can be construed as an outright threat. It is a distinction that Greeks and Romans might have applauded.

The comedies of Aristophanes (5th century bc) dealt with the issues of the day. They were characterised by language of Shakespearean inventiveness, covering the whole range of imaginable scatological, sexual and verbal abuse, aimed directly at named or easily recognisable individuals. Used in the street, such language would have met with a pretty instant, and probably violent, response. But, it seems, the conventions of public performance at the comic festival in honour of the god of theatre, Dionysus, made it permissible. Even the gods (including Dionysus) were lampooned (though never Athena).

But that does not mean that anything went. In 399 bc, Socrates was executed for ‘refusing to recognise the gods recognised by the state, and introducing other, new divinities [and] corrupting the young’. The state was at risk. We have only Socrates’ moving defence speech (the meaning of the Greek apologia), but the prosecution case was enough to persuade the jurors. Liberty and licence on stage were one thing; real life was different.

The Romans would have felt similarly. They were quite relaxed about worshipping whatever gods they came across, but they still insisted that the security of the state depended on regular ritual in honour of their own deities. For political reasons they made an uneasy exception of the Jews, but saw no reason to do so for Christians. They were a threat to state security. End of argument.

In the absence of conventions about satire, the ancients would have had no truck with Charlie Hebdo, which attacks the local god as keenly as alien ones, let alone with Islam, unless Muslims agreed to worship the local god as well. Today’s secular world, however, finds this all very difficult.