'Now you see,' Boniface whispered. 'Just as it says in the fourth stanza.'

'And the date? Does the Menologium predict that too?'

'Oh, yes. Look at the first stanza: the "men of gold", the "great king". We know that this refers to the coming of the Saxons at the invitation of the British great king, the Vortigem.'

'The brothers Hengist and Horsa,' she recited obediently, 'and their three ships.'

He snorted. 'Two legendary brothers, like Romulus and Remus. Two names which mean "horse" and "gelding". Remarkable how quickly history transmutes to myth! But the story is in Bede, even if he qualifies it… Using Bede and other sources we have dated this revolt to the four hundred and fifty-first year after the birth of Our Lord. We use the system of dating devised by the Scythian scholar Dionysius Exiguus, and made popular by Bede himself – although as Bede well knew that calculation incorporates errors.'

'Anno Domini four hundred and fifty-one,' Aelfric said. 'Then that is the date of the first stanza. Then the second, which follows nine-hundred and fifty-one months later-'

'Plus thirty-five, brings us to Anno Domini five hundred and thirty-three, and the death of Artorius, the Bear, the last great British leader.' He grinned, and his tumour crumpled, grotesque. 'It took an able computistor to work that out, believe me! The third stanza is dated at Anno Domini six hundred and seven, and appears to refer to the discovery of the Menologium itself. And then we come to the fourth stanza.'

She remembered Cuthbert's date from her studies. 'Anno Domini six hundred and eighty-four.'

'Precisely. But here's the remarkable thing, novice: the Menologium was written down more than two hundred years before the meeting of Cuthbert and Ecgfrith, and yet that meeting was prophesied to the correct year.'

She was chilled. 'Some say that prophecies and auguries and fortune-telling are the province of the Devil, not of God.'

'Ah, but here we have a text that was dedicated to Christ in its first stanza; we hold the word of God. It came to us by chance, you know – or by divine providence. A man called Wuffa found this document in an old fort on the Roman Wall. There was some murky business involving a Norse brute and a British whore, but Wuffa came away having learned the words of the prophecy, which he taught to his own children. He never got over whatever happened on the Wall. He was convinced he had somehow offended his god. He died, it seems, a poor and frightened man. When Wuffa's grandchild several times removed wandered into our grasp, a perspicacious brother realised what he had in his head, had the Menologium transcribed, and we have preserved it ever since. Of course that muddled grandchild never left, and became the last of the male line of Wuffa: all lines end here, however ancient.'

He leaned closer. 'Now do you see how important this is? Now do you see why we have such a strong case for the canonisation of Isolde? Now do you see why we middle generations labour to preserve this prophecy down through the ages which it describes? I told you I would explain to you our true purpose. It is as if we are steering an ark in this sea of barbarian darkness, until the light of empire burns brightly again – and it is the Weaver of time's tapestry who guides our way in the dark.'

She asked, 'Who is the Weaver?'

But he would not reply.

Aelfric's mind raced with implications. It made her feel odd, that long perspective – to think that she was a 'middle generation', her life dedicated to preserving relics produced by forefathers who were dust before she was born, for the benefit of children who would not see the light until long after her own death. But then wasn't that the Christian message, that each small life was dwarfed by the greater narrative of the universe?

And even if it were so, she thought now, was it possible that some of the Menologium's stanzas could refer to her own future?

'Dom, if the fourth stanza refers to Cuthbert, what does the fifth stanza mean?' She read it out from her smudged copy:

The Comet comes/in the month of May.

Great Year's midsummer/less nine of seven.

Old claw of dragon/pierces silence, steals words.

Nine hundred and twenty-one/the months of the fifth Year…

Fear brushed her mind, like the smoke of fire breath far away. 'A dragon's claw? Can this be a warning, Dom? A warning for us?'

'Ours is not to inquire,' he said.

'But the date – the midsummer of this fifth "Great Year" of nine hundred and twenty-one months, less nine sevens, which is sixty-three – you could work it out.'

'That is not for you,' he said firmly. 'The date is in God's mind, and mine. And there it must stay.'

After three days Macson submitted himself to the judgement of his priest and his peers, and his wound was judged to have healed well enough to prove him innocent. So he was free, and Belisarius kept his word.

They made their journey to the north in a hired cart drawn by two patient geldings and laden with Belisarius's precious books. Aboard rode the three of them, Belisarius, Macson – and Caradwc, Macson's father.

If Macson was around thirty, Belisarius judged, Caradwc must have been at least fifty. He rarely spoke. When he breathed his lungs bubbled, and he coughed up a spray of bloody droplets which Belisarius was careful to avoid. The Greek, armed only with his traveller's rough-and-ready medical knowledge, had no idea what was broken deep inside the old man, still less how to fix it.

There seemed an unusually strong bond between father and son. But then in Macson's eyes, Caradwc was more than just his father; he was the man who had bought the family out of slavery, after generations of too-well-remembered servitude. The old man's dying was hard for the son.

The journey north was easier than Belisarius had expected. As Macson had promised they generally made good time along the old Roman roads. But the legionaries had been gone for centuries, and in long stretches the roads had been robbed of their pavement stones, making the going uncomfortable. At least they were not troubled by bandits. Just as Macson had promised, the reign of the ageing Offa of Mercia had brought something resembling a rule of law to the island.

And this was May. The weather on this northern island was warmer than Belisarius had expected, and the greenery of the farmers' fields and the leaves of the forests, if stunted compared to the richness of the Mediterranean, the heart of the world, was pleasing to the eye. Unexpected, too, was the length of the days, which faded only subtly to dark, such was the northern latitude of the island.

It was a peculiar countryside for a former province of Rome. The hovel-like settlements of the Germans were everywhere. They could be close to the road, but never near a crossroads, for Macson, with some contempt, said the Germans were superstitious of crossroads, junction places where demons could escape. Sheep ran all over the place, and pigs rooted in forest patches. The animals looked small to Belisarius's eye; the pigs were long-legged, sharp-snouted, wild-looking. The Germans did not husband their animals as one did in the east – or indeed as the Romans once had here in Britain. Rather they let them run more or less wild, and harvested the slow and old in the autumn.

Many of the fields and common spaces were studded by crosses of stone, carved with intricate vine-like designs. Macson said these had been left by Christian missionaries, working their way out across Britain from Augustine's first landing site in the east. Though with time parish churches were being built, the first missionaries had set up these crosses as a place for their raw new German Christians to worship.