‘House breakage,’ said the boy. ‘Prices as marked.’ His Latin was coarse, simplified. He was perhaps sixteen, with a hard, surly expression. Thalius wasn’t frightened of him, but he was somehow disturbed. Here was a boy who had grown up almost outside society as Thalius had known it, with no compulsion to obey the rules of civilised discourse. What a resource for the future of Britain and the empire!

Thalius ran a finger over the scrolls. They were probably the debris of a minor tragedy, no doubt once owned by some member of the curia, more or less like himself, who had failed to maintain his balance in the endless cliff-top walk that was civil life these days.

But there were some interesting titles. One was a story called The True History by a Syrian-Greek called Lucian. Thalius had read it as a boy, and had since sought out other tales of fantastic voyages to strange corners of the world, or beyond the earth altogether - not myths, which always seemed a little hollow to him, but notions of what might actually be possible. But he had learned to keep his interest in these speculations quiet. Literary snobs always claimed that such tales were for adolescent boys, that the authors were running out of plots, and characterisation was sacrificed for the sake of ideas. It did Thalius no good to protest that the ideas were the whole point. With regret he replaced the Lucian; he already owned a better copy, though not one he kept on display.

As he browsed he was aware of a younger man beside him, also pushing through the heaps of scrolls. He jostled Thalius, to his intense irritation, as he tried to study the books.

The boy behind the counter took an interest in Thalius. ‘If you’re serious about buying, you might want to see this.’ He dug around under the table and produced a scroll even more dog-eared than the rest. Thalius, his eyes rheumy but still sharp, saw that it was a memoir by the Emperor Claudius. ‘Talks about his time here in Camulodunum. This is his Temple,’ he said, casually jerking his thumb over his shoulder.

‘I know whose Temple it is!’ snapped Thalius.

The boy was expressionless. ‘Good souvenir then.’

Thalius knew it was true that such an item was indeed difficult to find outside the great libraries of the Mediterranean cities - and even harder since Constantine had moved his capital hundreds of miles east. And he supposed the price would reflect its rarity. ‘Let me see it. Is it complete, good condition? What generation copy is it?’ Books nowadays were as tatty as everything else; you always had to check. He reached out for the scroll. The boy held it up before his chest. Grumbling at his lack of consideration, Thalius leaned forward over the table.