‘Why, it’s obvious - black powder. Haven’t you heard of it? The Chinese have studied it for centuries, we’re told. They call it the “fire drug”. It’s said they found it looking for an elixir of life! I had been hoping to obtain samples via the trade routes opened up by the Mongol empire, in order to verify its properties for myself. Now I can begin to experiment with its very manufacture.’

‘The manufacture of what?’ Joan demanded. ‘What does this stuff do, you infuriating monk?’

He didn’t seem insulted. ‘Well, if you set fire to it—’

‘Yes?’

‘It explodes.’

XXII

XXII

They sat around the low table, heaped with Bacon’s papers and covered with chalk scribbles.

‘Explodes,’ Joan said.

‘Somebody,’ Bacon said, ‘your Weaver of the tapestry of time, Thomas, wants you to make explosions. Incendium Dei indeed. I wonder why.’

Joan glanced at Thomas. ‘Have you told him of the engines?’

Thomas closed his eyes. ‘No. Because I did not have your permission. And because, frankly, I was frightened where it might lead, if he knew.’

Bacon’s eyes were wide. ‘What engines? You must tell me.’

Thomas glanced at Joan. ‘You see what I mean?’

Joan said, ‘Well, we are committed. And perhaps this strange monk of yours can help us.’ She described succinctly the legend of Sihtric and his machines of war, the plans now believed lost beneath the floor of the great mosque of Seville, in faraway al-Andalus.

‘But you must retrieve this Codex,’ Bacon said. ‘You must!’

‘Why?’

‘Can’t you see? Combine these engines of war, engines that roll and swim and even fly, with the black powder, with the Fire of God, and no man could stand before you. Think of it - a miniature Vesuvius loaded on each arrow! . . .’

Saladin’s experience of explosions was limited. But once he had seen a forge blow itself apart. He tried to imagine such energies harnessed, launched, and used against the flesh of enemies.

‘He’s right,’ he said reluctantly. ‘You told us, Thomas, that Sihtric was dissatisfied with the engines he made. Perhaps this black powder will provide the potency they always lacked.’

Thomas looked pale. ‘If it can be made to work - but what a horrible vision of destruction! What man is this Weaver to scatter the seeds of such carnage in our age?’