Khalid frowned.

Iwang tapped the book. 'This is just warmed over Aristotle. You can't trust him to tell you anything useful. I've read the translations out of Baghdad and Sevilla, and I judge he's wrong more often than he's right.'

'What do you mean?' Khalid cried indignantly. Even Bahram knew Aristotle was the wisest of the ancients, the supreme authority for all alchemists.

'Where is he not wrong?' Iwang said dismissively. 'The least country doctor in China can do more for you than Aristotle can. He thought the heart did the thinking, he didn't know it pumped the blood he has no idea of the spleen or the meridian lines, and he never says a word about the pulse or the tongue. He did some fair dissections of animals, but never dissected a human as far as I can tell. Come with me to the bazaar and I can show you five things he got wrong, any Friday you like.'

Khalid was frowning. 'Have you read Al Farudi's "Harmony Between Aristotle and Plato"?'

'Yes, but that is a harmony that can't be made. Al Farudi only made the attempt because he didn't have Aristotle's "Biology". If he knew that work, he would see that for Aristotle it all remains material. His four elements all try to reach their levels, and as they try, our world results. Obviously it's not that simple.' He gestured around at the bright dusty day and the clangour of Khalid's shop, the mills, the waterworks powering the big blast furnaces, the noise and movement. 'The Platonists knew that. They know it is all mathematical. Things happen by number. They should be called Pythagoreans, to be accurate. They are like Buddhists, in that for them the world is alive. As is obviously the case. A great creature of creatures. For Aristotle and Ibn Rashd, it's more like a broken clock.'

Khalid grumbled at this, but he was not in a good position to argue. His philosophy had been cut off with his hand.

He was often in some pain, and smoked hashish and drank Iwang's opiated potions to dull the pain, which also dulled his wits, which dulled his spirits. He could not leap in to teach the boys the proper uses of the machinery; he could not shake people's hands, or cat with others, having only his unclean hand left to him; he was permanently unclean. That was part of the punishment.

The realization of this, and the shattering of all his philosophical and alchemical inquiries, finally caught up with him, and cast him into a melancholia. He left his sleeping quarters late in the mornings, and moped around the works watching all the activity like a ghost of himself. There everything continued much as it had before. The great mills wheeled on the river's current, powering the ore stamps and the bellows of the blast furnaces. The crews of workers came in directly after the morning prayers, making their marks on the sheets that kept record of their work hours, then scattering through the compound to shovel salt or sift saltpetre, or perform any other of the hundred activities that Khalid's enterprises demanded, under the supervision of the group of old artisans who had helped Khalid to organize the various works.

But all this was known, accomplished, routinized, and meant nothing to Khalid any more. Wandering around aimlessly or sitting in his study, surrounded by his collections like a magpie in its nest with a broken wing, he would stare at nothing for hours, or else page through his manuscripts, Al Razid and jildaki and jami, looking at who knew what. He would flick a finger against the objects of wonder that used to fascinate him so – a chunk of pitted coral, a unicorn horn, ancient Indian coins, nested polygons of ivory and horn, a goblet made of a rhinoceros horn chased with gold leaf, stone shells, a tiger legbone, a gold tiger statue, a laughing Buddha made of some unidentified black material, Nipponese netsuke, forks and crucifixes from the lost civilization of Frengistan – all these objects, which used to give him such delight, and which he would discuss for hours in a manner that grew tedious to his regulars, now only seemed to irritate him. He sat amid his treasures and he was no longer on the hunt, as Bahram used to think of it, seeking resemblances, making conjectures and speculations. Bahram had not understood before how important this was to him.

As his mood grew blacker, Bahram went to the sufi ribat in the Registan, and asked Ali, the sufi master in charge of the place, about it. 'Mowlana, he has been punished worse than he thought at first. He's no longer the same man.'

'He is the same soul,' said Ali. 'You are simply seeing another aspect of him. There is a secret core in everyone that not even Gabriel can know by trying to know. Listen now. The intellect derives from the senses, which are limited, and come from the body. The intellect therefore is also limited, and it can never truly know reality, which is infinite and eternal. Khalid wanted to know reality with his intellect, and he can't. Now he knows that, and is downcast. Intellect has no real mettle, you see, and at the first threat, into a hole it scuttles. But love is divine. It comes from the realm of the infinite, and is entrusted to the heart as a gift from God. Love has no calculating in it. "God loves you" is the only possible sentence! So it's love you must follow to the heart of your father in law. Love is the pearl of an oyster living in the ocean, and intellect lives on the shore and cannot swim. Bring up the oyster, sew the pearl onto your sleeve for all to see. It will bring courage to the intellect. Love is the king that must rescue his coward slave. Do you understand?'

'I think so.'

'You must be sincere and open, your love must be bright as the lightning flash itself! Then his inner consciousness might see it, and be snatched from itself in a twinkling. Go, feel the love course through you, and out to him.'

Bahram tried this strategy. Waking in his bed with Esmerine, he felt the love rising in him, for his wife and her beautiful body, the child after all of the mutilated old man he regarded so fondly. Full of love, he would make his way through the workshops or into town, feeling the cool of the springtime air on his skin, and the trees around the pools would gleam dustily, like great living jewels, and the intense white clouds would accentuate the deep blue of the sky, echoed underneath by the turquoise and cobalt tiles of the mosque domes.

Beautiful town on a beautiful morning, at the very centre of the world and the bazaar its usual massed chaos of noise and colour, all human intercourse there to be seen at once, and yet pointless as an anthill, unless it was infused with love. Everyone did what they did for love of the people in their lives, day after day – or so it seemed to Bahram on those mornings, as he took on more of Khalid's old assignments at the compound – and in the nights too, as Esmerine enfolded him.

But he could not seem to convey this apprehension to Khalid. The old man snarled at any expression of high spirits, much less love, and became irritated at any gesture of affection, not just from Bahram but from his wife Fedwa, or Esmerine, or Bahram and Esmerine's children, Fazi and Laila, or anyone else. The bustle of the workshops would surround them in the sunlight with their clangour and stink, all the protocols of metalworking and gunpowder making that Khalid had formulated going on before them as if in a giant loud dance, and Bahram would make a gesture encompassing it all and say, 'Love fills all this so full!' and Khalid would snarl, 'Shut up! Don't be a fool!'

One day he slammed out of his study with his single hand holding two of his old alchemical texts, and threw them into the door of a blazing athanor. 'Complete nonsense,' he replied bitterly when Bahram cried out for him to stop. 'Get out of my way, I'm burning them all.'

'But why?' Bahram cried. 'Those are your books! Why, why, why?'

Khalid took a lump of dusty cinnabar in his one hand, and shook it before Bahram. 'Why? I'll tell you why! Look at this! All the great alchemists, from jabir to al Razi to Ibn Sina, all agree that all the metals are various combinations of sulphur and mercury. Iwang says the Chinese and Hindu alchemists agree on this matter. But when we combine sulphur and mercury, as pure as we can make them, we get exactly this: cinnabar! What does that mean? The alchemists who actually speak to this problem, who are very few I might add, say that when they talk about sulphur and mercury, they don't really mean the substances we usually call sulphur and mercury, but rather purer elements of dryness and moisture, that are like sulphur and mercury, but finer! Well!' He threw the chunk of cinnabar across the yard at the river. 'What use is that? Why even call them that? Why believe anything they say?' He waved his stump at his study and alchemical workshop, and all the apparatus littering the yard outside. 'It's all so much junk. We don't know anything. They never knew what they were talking about.'