Khalid nodded. 'Thus the stars may have their sway over us after all. Maybe the stars are animals too, like these creatures, could we only see them better.'

Iwang shook his head. 'All one, yes. It seems more and more obvious. But not all animal, surely. Perhaps the stars are more like rocks than these fine creatures.'

'The stars are fire.'

'Rocks, fire – but not animals.'

'But all one,' Bahram insisted.

And both of the older men nodded, Khalid emphatically, Iwang reluctantly, and with a low humming in his throat.

After that day it seemed to Bahram that Iwang was always humming. He came to the compound and joined Khalid in his demonstrations, and went with Bahram to the ribat and listened to Ali's lectures, and whenever Bahram visited him in his shop he was playing with numbers, or clicking a Chinese abacus back and forth, and always distracted, always humming. On Fridays he came to the mosque and stood outside the door, listening to the prayers and the readings, facing Mecca and blinking at the sun, but never kneeling or prostrating or praying; and always humming.

Bahram did not think he should convert. Even if he had to move back to Tibet for a time and then return, it seemed clear to Bahram that he was no Muslim. And so it would not be right.

Indeed, as the weeks passed he began to seem more strange and foreign, rather than less; even more an unbeliever, performing little demonstrations for himself that were like sacrifices to light, or magnetism, or the void, or gravity. An alchemist, precisely, but in an eastern tradition stranger than any sufi's, as if he were not only reverting to Buddhism but going beyond it, back to Tibet's older religion, Bon as Iwang called it.

That winter he sat in his shop with Bahram, before the open fire of his furnace, hands extended to keep the fingers warm as they poked out of the glove ends like his little babies, smoking hashish from a longstemmed pipe and handling it to Bahram occasionally, until the two men sat there watching the coals' film dance over the hot orange underneath. One night, deep in a snowstorm, Iwang went out to get more wood for the fire, and Bahram looked over at a movement and saw an old Chinese woman sitting by the stove, dressed in a red dress, with her hair pulled up in a knot on top of her head. Bahram jerked; the old woman turned her head and looked at him, and he saw her black eyes were filled with stars. He promptly fell off his stool, and groped to his feet to find her no longer there. When Iwang came back in the room and Bahram described her, Iwang shrugged, smiled slyly: 'There are lots of old women in this quarter of the city. This is where the poor people live, among them the widows, who have to sleep in their dead husbands' shops on the floor, on the sufferance of the new owners, and do what they can to keep hunger from the door.'

'But the red dress – her face – her eyes!'

'That all sounds like the goddess of the stove, actually. She appears next to the hearth, if you're lucky.'

'I'm not smoking any more of your hashish.'

Iwang laughed. 'If only that was all it took!'

Another frosty night, a few weeks alter, Iwang knocked on the gate of the compound, and came in greatly excited – drunk, one would have said of another man – a man possessed.

'Look!' he said to Khalid, taking him by his shortened arm and pulling him into the old man's study. 'Look, I've worked it out at last.'

'The philosopher's stone?'

'No no! Nothing so trivial! It's the one law, the law above all the others. An equation. See here.'

He got out a slate and chalked on it rapidly, using the alchemical symbols Khalid and he had decided on to mark quantities that were different in different situations.

'Same above, same below, just as Bahram is always saying. Everything is attracted to everything else by precisely this level of attraction. Multiply the two masses attracting each other, divide that by the square of the distance they are apart from each other multiply by whatever speed away from the central body there might be, and the force of the attraction results. Here – try it with the planets' orbits around the sun, they all work. And they travel in ellipses around the sun, because they all attract each other as well as being pulled down to the sun, so the sun sits at one focus of the ellipse, while the sum of all other attractions make the other focus.' He was sketching furiously as he spoke, as agitated as Bahram had ever seen him. 'It explains the discrepancies in the observations out at Ulug Beg. It works for the planets, the stars in their constellations no doubt, and the flight of a cannonball over the Earth, and the movement of those little animalcules in pondwater or in our blood!'

Khalid was nodding. 'This is the power of gravity itself, portrayed mathematically.'

'Yes.'

'The attraction is in inverse proportion to the square of the distance away.'

'Yes.'

'And it acts on everything.'

'I think so.'

'What about light?'

'I don't know. Light itself must have so little mass. If any. But what mass it has, is being attracted to all other masses. Mass attracts mass.'

'But this,' Khalid said, 'is again action at a distance.'

'Yes.' Iwang grinned. 'Your universal spirit, perhaps. Acting through some agency we don't know. Thus gravity, magnetism, lightning.'

'A kind of invisible fire.'

'Or perhaps to fire as the tiniest animals are to us. Some subtle force.

And yet nothing escapes it. Everything has it. We all live within it.'

'An active spirit in all things.'

'Like love,' Bahram put in.

'Yes, like love,' Iwang agreed for once. 'In that without it, all would be dead on Earth. Nothing would attract or repel, or circulate, or change form, or live in any way, but merely lie there, dead and cold.'

And then he smiled, he grinned outright, his smooth shiny Tibetan cheeks dimpled by deep creases, his big horsey teeth gleaming: 'And here we are! So it must be, do you see? It all moves – it all lives. And the force acts exactly in inverse proportion to the distance between things.'

Khalid began, 'I wonder if this could help us to transmute But the other two men cut him off: 'Lead into gold! Lead into gold!' Laughing at him.

'It's all gold already,' Bahram said, and Iwang's eyes suddenly gleamed, it was as if the goddess of the stove had filled him, he pulled Bahram to him and gave him a rough wet woolly hug, humming again.

'You're a good man, Bahram. A very good man you are. Listen, if I believe in your love, can I stay here? Will it be blasphemy to you, if I believe in gravity and love, and the oneness of all things?'

Theories without Application

Make Trouble

Bahram's days became busier than ever, as was true for everyone in the compound. Khalid and Iwang continued to debate the ramifications of Iwang's great figure, and to run demonstrations of all kinds, either testing it or investigating matters related to it. But their investigations did little to help Bahram in his work at the forge, it being difficult or impossible to apply the two explorers' esoteric and highly mathematical arguments to the daily effort to make stronger steel or more powerful cannons. To the Khan, bigger was better, and he had heard of new cannons of the Chinese Emperor, that dwarfed even the old giants left stranded in Byzantium by the great plagues of the seventh century. Bahram was trying to match these rumoured guns, and finding it hard to cast them, hard to move them, and hard to fire them without causing them to crack. Khalid and Iwang both had suggestions, but these did not work out, and Bahram was left with the same old trial and error that metallurgists had used for centuries, always coming back to the idea that if he could only get the molten iron hot enough, and of the right mix of feed stocks, then the resulting metal of the cannon would be stronger. So it was a matter of increasing the amount of the river's force applied to the blast furnaces, to create temperatures that turned the melts incandescent white, so brilliant it hurt to look at them. Khalid and Iwang observed the scene at dusk, and argued till dawn about the origins of such vivid light, released out of iron by heat.