Thalius could see a lot of barter going on, rather than cash sales - half a chicken for a pretty bit of jade, a scrip promising a day’s labour on a thatched roof in return for a much-used, much-repaired amphora. Those who did have cash hoarded it, out of sight of the tax collectors, but Thalius was aware that the collectors and their spies were probably circulating through the marketplace even now. In an age when even the army was prepared to accept payments in kind, a black market didn’t stay black for long. The market was a vastly unpleasant place to Thalius, making him feel like a mouse among a swarm of mice feeding off each other’s garbage.

The people around him were unpleasant too. Almost all of them younger than him - well, he had been used to that for years - and they were coarse, uncivil, disrespectful to each other and worse to old duffers like Thalius. It was an age of selfishness, he thought, an age of ill manners. And it was all because of Constantine. Poor, foolish, long-dead Aurelia had been right, in her narrow way. The burden of excessive taxation, the huge and still growing gulf between rich and poor, had coarsened society at every level. But what other way was there?

Here, though, amid all the rubbish, was a table piled high with books. There were scrolls, heaps of wood slips, even some densely inscribed wax tablets. Thalius began to rummage; it was a relief simply to be handling books. But none was mint, and some didn’t even look complete. And very many of them were utterly uninteresting (to him) treatises on various aspects of the Christian faith.

There was an awful lot of this stuff around. After Constantine’s imposition of Christianity his bishops and theologians, drunk on sudden power and money, indulged in ferocious infighting over heresies and counter-heresies. People were addled by intriguing theological complexities, and nowadays read only the Bible and commentaries on it - if they read anything at all. And as the numbers of the illiterate grew, and as the literate retreated into mysticism, nobody thought any more, nobody questioned, nobody remembered that things had ever been different from the way they were now.

But Thalius quickly identified a Tacitus, a Pliny, a Cicero, relics of an age when people could still think, and argue, and write.

He looked into the gloom of the covered stall behind the table. A youth sat on a stool, chewing on some herb, watching a girl on the next stall with a lascivious leer. Thalius snapped his fingers. ‘You!’

The boy’s head swivelled to face him. ‘You’re talking to me?’

‘Not by choice, but it does seem you’re the purveyor of these books. What is their provenance?’

The boy scowled. ‘What?’

Thalius sighed. ‘Are you selling these books? Where did they come from?’