Inside the Night, Inside the Light
This unenthusiastic response on the part of the Khan worried Bahram. No interest in an apparatus that had fascinated the scholars of the madressa; instead, a command to discover some new weapon or fortification that had eluded the hard search of all the armourers of all the ages. And if they failed, the possible punishments were only too easy to imagine. Khalid's absent hand mocked them from its own kind of void. Khalid would stare at the end of his wrist and say, 'Someday all of me will look like you.'
Now he merely looked around the compound. 'Tell Paxtakor to obtain new cannon from Nadir for testing. Three at each weight, and all manner of powder and shot.'
'We have powder here.'
'Of course.' A withering glare: 'I want to see what they have that is not ours.'
In the days that followed, he revisited all the old buildings of the compounds, the ones he and his old ironmongers had built when they were first making guns and gunpowder for the Khan. In those days, before he and his men had followed the Chinese system and connected the power of their waterwheel to the furnaces, making their first riverpowered blast furnaces and freeing up their crew of young puffers for other work, everything had been small and primitive, the iron more brittle, everything they made rougher, bulkier. The buildings themselves showed it. Now the gears of the waterwheels whirred with all the power of the river, pouring into the bellows and roaring as fire. The chemical pits steamed lemon and lime in the sun, and the puffers packed boxes and ran camels and moved immense mounds of charcoal around the yards. Khalid shook his head at the sight of it all, and made a new gesture, a kind of sweep and punch with his ghost hand. 'We need better clocks. We can only make progress if our measurement of time is more exact.'
Iwang puffed his lips when he heard this. 'We need more understanding.'
'Yes, yes, of course. Who could dispute that in this miserable world. But all the wisdom of the ages cannot tell us how long it takes flashpowder to ignite a charge.'
When the days ended the great compound fell silent, except for the grinding of the watermill on the canal. After the resident workers had washed and eaten and said their last prayers of the day, they went to their apartments at the river end of the compound, and fell asleep. The town workers went home.
Bahram dropped onto his bed beside Esmerine, across the room from their two small children, Fazi and Laila. Most nights he was out as soon his head hit the silk of his pillow, exhausted. Blessed slumber.
But often he and Esmerine woke some time after midnight, and sometimes they lay there breathing, touching, whispering conversations that were usually brief and disjointed, other times the longest and deepest conversations they ever had; and if ever they were to make love, now that the children were there to exhaust Esmerine, it would be in the blessed cool and quiet of these midnight hours.
Afterwards Bahram might get up and walk around the compound, to see it in moonlight and check that all was well, feeling the afterglow of love pulse in him; and usually on these occasions he would see the lamplight in Khalid's study, and pad by to find Khalid slumped over a book, or scribbling left handed at his writing stand, or recumbent on his couch, in murmured conversation with Iwang, both of them holding tubes of a narghile wreathed by the sweet smell of hashish. If Iwang was there and the men seemed awake, Bahram would sometimes join them for a while, before he got sleepy again and returned to Esmerine. Khalid and Iwang might be speaking of the nature of motion, or the nature of vision, sometimes holding up one of Iwang's lenses to look through as they talked. Khalid held the position that the eye received small impressions or images of things, sent through the air to it. He had found many an old philosopher, from China to Frengistan, who held the same view, calling the little images 'eidola' or 'simulacra' or 'species' or 'image' or 'idol' or 'phantasm' or 'form' or 'intention' or 'passion' or,similitude of the agent', or 'shadow of the philosophers', a name that made Iwang smile. He himself believed the eye sent out projections of a fluid as quick as light itself, which returned to the eye like an echo, with the contours of objects and their colours intact.
Bahram always maintained that none of these explanations was adequate. Vision could not be explained by optics, he would say; sight was a matter of spirit. The two men would hear him out, then Khalid would shake his head. 'Perhaps optics are not sufficient to explain it, but they are necessary to begin an explanation. It's the part of the phenomenon that can be tested, you see, and described mathematically, if we are clever enough.'
The cannons arrived from the Khan, and Khalid spent part of every day out on the bluff over the curve in the river, shooting them off with old jalil and Paxtakor; but by far the bulk of his time was spent thinking about optics and proposing tests to Iwang. Iwang returned to his shop, blowing thick glass balls with cut sides, mirrors concave and convex, and big, perfectly polished triangular rods, which were for him objects of almost religious reverence. He and Khalid spent afternoon hours in the old man's study with the door closed, having made a little hole in the south wall letting in a chink of light. They put the prism over the hole, and its straight rainbow shone on the walls or a screen they set up. Iwang said there were seven colours, Khalid six, as he called Iwang's purple and lavender two parts of the same colour. They argued endlessly about everything they saw, at least at first. Iwang made diagrams of their arrangement that gave the precise angles each band of colour bent as it went through the prism. They held up glass balls and wondered why the light did not fractionate in these balls as it did in the prism, when everyone could see that a sky full of minuscule clear balls, that is to say raindrops, hit by low afternoon sunlight, created the towering rainbows that hung east of Samarqand after a rainshower had passed. Many a time when black storms had passed over the city, Bahram stood outside with the two older men observing some truly beautiful rainbows, often double rainbows, a lighter one arched over the brighter one; and sometimes even a third very faint one above that. Eventually Iwang worked up a law of refraction which he assured Khalid would account for all the colours. 'The primary rainbow is produced by a refraction as the light enters the raindrop, an internal reflection at the back surfaces, and a second refraction out of the raindrop. The secondary bow is created by light reflected two or three times inside the raindrops. Now look you, each colour has its own index of refraction, and so to bounce around inside the raindrop is to separate each colour out from the others, with them appearing to the eye always in their correct sequence, reversed in the secondary because there is an extra bounce making it upside down, as in my drawing here, see?'
'So if raindrops were crystalline, there would be no rainbows.'
'That's right, yes. That's snow. If there was only reflection, the sky might sparkle everywhere with white light, as if filled with mirrors. Sometimes you see that in a snowstorm, too. But the roundness of raindrops means there is a steady change in the angle of incidence between zero and ninety degrees, and that spreads the different rays to an observer here, who must always stand at an angle from forty to fortytwo degrees off from the incoming sunlight. The secondary one appears when the angle is between fifty and a half degrees and fifty four and a half. See, the geometry predicts the angles, and out here we measure, using this wonderful sky viewer Bahram found for you at the Chinese caravanserai, and it confirms, as precisely as hand can hold, the mathematical prediction!'
'Well, of course,' Khalid said, 'but that's circular reasoning. You get your angles of incidence by observation of a prism, then confirm the angles in the sky by more observation.'
'But one was colours on the wall, the other rainbows in the sky!'
'As above, so below.' This of course was a truism of the alchemists, so there was a dark edge to Khalid's comment.
The current rainbow was waning as a cloud in the west blocked the sun. The two old men did not notice, however, absorbed as they were in their discussion. Bahram alone was left to enjoy the vibrant colours arcing across the sky, Allah's gift to show that he would never again dr
own the world. The two men jabbed fingers at Iwang's chalkboard and Khalid's sky device.
'It's leaving,' Bahram said, and they looked up, slightly annoyed to be interrupted. While the rainbow had been bright, the sky under it had been distinctly lighter than the sky over it; now the inside and outside were the same shade of slate blue again.
The rainbow left the world, and they squelched back to the compound, Khalid cheering up with every step, many of them right into puddles, as he was still staring at Iwang's chalkboard.
'So – so – well. I must admit, it is as neat as a proof of Euclid. Two refractions, two or three reflections – rain and sun, an observer to see – and there you have it! The rainbow!'
'And light itself, divisible into a banding of colours,' Iwang mused, travelling all together out of the sun. So bright it is! And when it strikes anything at all, it bounces off and into an eye, if there be an eye to see it, and whatever part of the band, hmm, how would that work… are the surfaces of the world all variously rounded, if you could but look at them close enough…'
'It's a wonder things don't change colour when you move,' Bahram said, and the other two went silent, until Khalid started laughing.
'Another mystery! Allah preserve us! They will just keep coming for ever, until we are one with God.'
This thought appeared to please him immensely.
He set up a permanent dark room in the compound, all boarded and draped until it was much darker than his study had been, with shuttered chinks in the east wall that could let in small shafts of light, and many a morning he was in there with assistants, running in and out, arranging demonstrations one way or another. One he was pleased enough with to invite the scholars of the Sher Dor Madressa to witness it, because it so neatly refuted Ibn Rashd's contention that white light was whole, and the colours created by a prism an effect of the glass. If this were so, Khalid argued, then light twice bent would change colour twice. To test this, his assistants allowed sunlight in through the wall, and a first prism's array was spread across a screen in the centre of the room. Khalid himself opened an aperture in the screen small enough only to allow the red part of the little rainbow through it, into a draped closet where it immediately encountered another prism, directing it onto another screen inside the closet.
'Now, if the bend of refraction caused by itself the change in colour, surely the red band would change at this second refraction. But look: it remains red. Each of the colours holds when put through a second prism.'
He moved the aperture slowly from colour to colour, to demonstrate. His guests crowded around the door of the closet, examining the results closely.
'What does this mean?' one asked.
'Well, this you must help me with, or ask Iwang. I am no philosopher, myself. But I think it proves the change in colour is not just a matter of bending in itself. I think it shows sunlight, white light if you will, or full light, or simply sunlight, is composed of all the individual colours travelling together.'
The witnesses nodded. Khalid ordered the room opened up, and they retired blinking into the sun to have coffee and cakes.
'This is wonderful,' Zahhar, one of Sher Dor's senior mathematicians said, 'very illuminating, so to speak. But what does it tell us about light, do you think? What is light?'
Khalid shrugged. 'God knows, but not men. I think only that we have clarified (so to speak) some of light's behaviour. And that behaviour has a geometrical aspect. It seems regulated by number, you see. As do so many things in this world. Allah appears to like mathematics, as you yourself have often said, Zahhar. As for the substance of light, what a mystery! It moves quickly, how quickly we do not know; it would be good to find out. And it is hot, as we know by the sun. And it will cross a void, if indeed there is any such thing as a void in this world, in a way that sound will not. It could be that the Hindus are right and there is another element besides earth, fire, air and water, an ether so fine we do not see it, that fills the universe to a plenum and is the medium of movement. Perhaps little corpuscles, bouncing off whatever they strike, as in a mirror, but usually less directly. Depending on what it strikes, a particular colour band is reflected into the eye. Perhaps.' He shrugged. 'It is a mystery.'
The Madressas Weigh In
The colour demonstrations caused a great deal of discussion and debate in the madressas, and Khalid learned during this period never to speak of causes in any opinionated way, or to impinge on the realm of the madressa scholars by speaking of Allah's will, or any other aspect of the nature of reality. He would only say, 'Allah gave us our intelligence to better understand the glory of his work,' or, 'the world often works mathematically. Allah loves numbers, and mosquitos in springtime, and beauty.'
The scholars went away amused, or irritated, but in any case in a ferment of philosophy. The madressas of Registan Square and elsewhere in the city, and out at Ulug Bek's old observatory, were buzzing with the new fashion of making demonstrations of various physical phenomena, and Khalid's was not the only mechanical workshop that could build an ever more complex array of new machines and devices. The mathematicians of Sher Dor Madressa, for instance, interested everyone with a surprising new mercury scale, simple to construct a bowl containing a pool of mercury, with a narrow tube of mercury, scaled at the top but not the bottom, set upright in the liquid in the bowl. The mercury in the tube dropped a certain distance, creating another mysterious void in the gap left at the top of the tube; but the remainder of the tube stayed filled with a column of mercury. The Sher Dor mathematicians asserted that it was the weight of the world's air on the mercury in the bowl that pushed down on it enough to keep the mercury in the cylinder from falling all the way down into the bowl. Others maintained it was the disinclination of the void in the top of the tube to grow. Following a suggestion of Iwang's, they took their device to the top of Snow Mountain, in the Zeravshan Range, and all there saw that the level of mercury in the tube had dropped, presumably because there was less weight of air on it up there, two or three thousand hands higher than the city. This was a great support for Khalid's previous contention that air weighed on them, and a refutation of Aristotle, and al Farabi and the rest of the Aristotelian Arabs, who claimed that the four elements want to be in their proper places, high or low. This claim Khalid ridiculed, at least in private. 'As if stones or the wind could want to be some place or other, as a man does. It's really nothing but circular definition again. "Things fall because they want to fall", as if they could want. Things fall because they fall, that's all it means. Which is fine, no one knows why things fall, certainly not me, it is a very great mystery. All the seeming cases of action at a distance are a mystery. But first we must say so, we must distinguish the mysteries as mysteries, and proceed from there, demonstrating what happens, and then seeing if that leads us to any thoughts concerning the how or the why.'
The sufi scholars were still inclined to extrapolate from any given demonstration to the ultimate nature of the cosmos, while the mathematically inclined were fascinated by the purely numerical aspects of the results, the geometry of the world as it was revealed. These and other approaches combined in a burst of activity, consisting of demonstrations and talk, and private work on slates over mathematical formulations, and artisanal labour on new or improved devices. On some days it seemed to Bahram that these investigations had filled all Samarqand: Khalid's compound and the others, the madressas, the ribat, the bazaars, the coffee stalls, the caravanserai, where the traders would take the news out to all the world… it was beautiful.
The Chest of Wisdom
Out beyond the western wall of the city, where the old Silk Road ran towards Bokhara, the Armenians were quiet in their little caravanserai, tucked beside the large and raucous Hindu one. The Armenians were cooking in the dusk over their braziers. Their women were bare headed and bold eyed, laughing among themselves in their own language. Armenians were good traders, and yet reclusive for all that. They trafficked only in the most expensive goods, and knew everything about ev
erywhere, it seemed. Of all the trading peoples, they were the most rich and powerful. Unlike the Jews and Nestorians and Zott, they had a little homeland in the Caucasus to which most of them regularly returned, and they were Muslim, most of them, which gave them a tremendous advantage across Dar al Islam which was to say all the world, except for China, and India below the Deccan. Rumours that they only pretended to be Muslim, and were secretly Christians all the while, struck Bahram as envious backstabbing by other traders, probably the tricky Zott, who had been cast out of India long before (some said Egypt), and now wandered the world homeless, and did not like the Armenians' inside position in so many of the most lucrative markets and products.
Bahram wandered among their fires and lamplight, stopping to chat and accept a swallow of wine with familiars of his, until an old man pointed out the bookseller Mantuni, even older, a wizened hunchbacked little man who wore spectacles that made his eyes appear the size of lemons. His Turkic was basic and heavily accented, and Bahram switched to Persian, which Mantuni acknowledged with a grateful dip of the head. The old man indicated a wooden box on the ground, filled entirely with books he had obtained for Khalid in Frengistan. 'Will you be able to carry it?' he asked Bahram anxiously.
'Sure,' Bahram said, but he had his own worry: 'How much is this going to cost?'
'Oh no, it's already paid for. Khalid sent me off with the funds, otherwise I would not have been able to afford to buy these. They're from an estate sale in Damascus, a very old alchemical family that came to an end with a hermit who had no issue. See here, Zosimos' 'Treatise on Instruments and Furnaces", printed just two years ago, that's for you. I've got the rest arranged chronologically by date of composition, as you can see, here is Jabir's "Sum of perfection", and his "Ten Books of Rectification", and look, 'The Secret of Creation".'
The Year of Rice and Salt Page 26
