Thalius led the way to the kitchen, where Tarcho was looking after the boy. He was greeted at the door by the warm smell of cooking bread. Inside, Tarcho was pounding vegetables with a mortar and pestle. Audax, standing close by, watched, fascinated. On a whim, Thalius paused, and his guests waited behind him, curious.

Thalius heard Audax say to Tarcho, 'You didn't squash beets when you were a soldier.' He was proving a fast learner, but his Latin was still rudimentary, uncertain, his accent strong, his abused throat gravelly.

'Oh, I did, and more. Soldiers do everything for themselves.'

'Soldiers fight.'

'Well, not all the time! And in between fighting we do other things. We build forts and lay roads and build bridges.'

'And squash beets.'

'We squash beets and lay roads.'

'Do you work in mines?'

'Sometimes.'

Audax pulled a face. 'Why would you work in a mine?'

'Well, you have to, if you're ordered to.'

'A soldier is like a slave, then. You have to do what you're told.'

Tarcho faced the boy. 'No. Never like that. A soldier is free in a way a slave never can be. It's a good life.'

'Why is it so good?'

'Because the emperors need us. The whole of the empire, all of it, the cities and the walls and the forts, is like one vast farmyard designed to feed the army. Why? Because without us it would all collapse in a day. Have you heard of an emperor called Severus?'

'Who?'

'Came to Britain to put down a rising.'

'Carausias?'

'No, long before him. While he was here Severus took the whole of Britain, far to the north of the Wall, then his sons gave it away again. Long story. Anyhow Severus had to sort out a mess, and it was the army that sorted it for him, and Severus knew it. "Feed the soldiers," he told his sons, "and let the rest rot." Or words to that effect. Dead a hundred years, but he was right. And every emperor since has followed his advice.'

'Should I join the army, Tarcho?'

Tarcho looked at the boy, surprised. 'Well, you'd have to be bought out of your slavery…Is that what you want? You'd have to fight for Rome, you know.'

'That wouldn't make me Roman.'

'No, true. But if you aren't Roman, what are you?'

'What I always was. Brigantian.'

So, Thalius heard, fascinated, under the surface of Britannia the old nations survived, if only in the memory of slaves.

Audax said now, 'I want to be like you. I've got the muscles. Look.' He held up an arm, pitifully thin, and bent it to show a bicep like a walnut.

Tarcho grinned, and in a brief and uncharacteristic moment of tenderness, hugged the boy against his own massive chest.

'Sweet to watch them,' Aurelia whispered. 'Like seeing an eight-year-old care for a three-year-old.'

Cornelius murmured, 'I suggest we get on with our business, Thalius.'

Thalius took a breath. 'Very well.' He coughed loudly to announce his presence and walked into the kitchen.

Tarcho stood, surprised, dropping the mortar and pestle. Audax hid behind Tarcho. The kitchen staff were startled, and Thalius waved a hand at them, shooing them out.

Tarcho stepped forward. 'Sir, is there something I can do for you?'

Thalius sighed. 'Not you but your charge, I'm afraid. Audax! Step forward now.'

The slave obeyed without thinking, his head bowed. Tarcho stayed a step behind him.

Thalius bent and whispered, 'I'm sorry about this, lad. You must show your back again. But it won't be for long, and I promise you won't be hurt. Is that all right?'

The boy didn't reply. For all Tarcho's good will the boy's spirit remained a flicker.

Thalius straightened up. 'Turn around and lift your tunic. You know what to do.'

The boy leaned forward to expose the grid of letters he had borne all his life but never seen:

Cornelius, bending stiffly, inspected the boy. 'Tell me again where this thing came from, Thalius?'

Thalius shrugged. 'I have only legends, passed down for generations. The original Prophecy was a poem, sixteen lines long. It was burned at Hadrian's orders. But it contained an acrostic-the first letter of each line, perhaps making up the core of the Prophecy's message-that was remembered and passed on. And then, at some later time, it was encoded into this grid form.'

'Then this mass of scars is all that is left of your famous Prophecy.' Cornelius peered, pointing to the letters with his finger. 'Well, if it's an acrostic it's cleverer than the one on your wall, Thalius. That one made sense whether you read it up or down, back or forth. This one doesn't make sense any which way!'

'But I think it does,' Aurelia said. Tension shaped her aged, vulpine face, and Thalius wondered how he could ever have found her attractive. She said, 'It is how I visualised it, but now I can see it-here, see the A and O in the lower left, upper right corners. Alpha and omega-remember? This is an acrostic compiled by and for Christians, just like the Pater Noster.'

But how could that be? Thalius wondered, chilled. For if the old legends were correct the acrostic came from a poem written down in the year of the birth of Christ, when there were no Christians.

Cornelius said, 'But there is another A, another O-never mind! Can you decipher this jumble?'

'With the start and end points of the A and O, I think I can, yes.'

'Then do it, woman!'

Aurelia paused, staring at the scar for a long breath. Suddenly, quite uncharacteristically, she seemed hesitant. 'First we must be sure we want to know.' She turned away from the boy. 'You Romans have a word for such a moment as this, Cornelius: discrimen, a crucial, life-shaping decision, a choice that might lead to triumph or catastrophe. Even if I can read the Prophecy, should we follow its advice? Constantine's elevation may be the most significant event ever to have occurred in Britannia. Rome is the world's greatest power, and decisions made by emperors cause history to shudder. And now we propose to deflect an emperor from his mighty path. History's Weaver may want this, but do we? Are we sure? Cornelius?'

Cornelius considered. 'If left unchecked this emperor will dissipate the very strengths that have made Rome strong. Rome must rediscover itself-and if Constantine is the man to lead that revival I will be happy. But he must be shown the way. And you, madam?'

'I am concerned for Britain. We are being taxed to death. And if the heart of the empire is moved east, the west could wither. Yes, he must be deflected before his course is set. I'm sure. And you, Thalius? Will you follow the Prophecy?'

Thalius, heart thumping, tried to think it through.

The others forever took a partial view, it seemed to him. The fact was the world was a different place from the arena in which Rome had achieved its first dazzling successes. Now there was no room to expand, and from the heart of Asia whole peoples were on the march, fleeing drought and famine.

The Romans were not technical innovators, but, Thalius believed, they were social innovators. They had already put themselves through one vast transformation, when the pressures of running their huge acquisitions had become too great for the fraught political processes of a republic, and the emperors had been hatched. Now in response to the pressures of a new age, Constantine was attempting a still more drastic metamorphosis as he tried to weld a conglomeration of differently developed provinces into a single nation, tightly controlled under one man's authority, and bound together by the theological cement of Christianity. It seemed to Thalius that Constantine might be hailed by future generations as truly great, as a genius of his kind.