As the Arab empire grew to encompass Afghanistan in the East and Spain in the West, a huge revival in learning occurred, a true renaissance. It was in this tradition that Ibn al-Haytham was brought up. Without visiting Egypt he wrote a book on civil engineering in which he claimed he could build a dam and a series of canals and levees to control the annual flooding of the Nile. He wrote, ‘Had I been in Egypt, I could have done something to regulate the Nile so that people could derive benefit at its ebb and flow.’ Living in Basra, in what is now Iraq, he probably felt this theoretical pronouncement would never be tested. But he had reckoned without the madness of Caliph Hakim of Egypt.
Hakim’s ‘eccentricities’ were legendary. He once had all the dogs of Cairo executed because their barking was driving him mad. Or maybe madder. (Having seen the feral-dog problem of Cairo first hand, I can offer a smidgin of sympathy here.) But it gets worse. Hakim persecuted not only Christians, but also Jews and Muslims – equally. He destroyed the ancient city of Fustat, the original Arab capital of Cairo, because its orientation ‘displeased him’. He built a great library in Cairo to rival the House of Wisdom in Baghdad; then he sacked the Church of the Resurrection in Jerusalem. At night he would wander in disguise in the hills of Moqattam, said to be the haunt of mystics and madmen.
Ibn al-Haytham can’t have been too thrilled when, comfortably sitting in Basra teaching the sons of the wealthy, he received a letter. His next job offer – dam the Nile. Only, it was less of an offer and more of an order, an order from a notoriously unstable ruler. But the engineer in him ignored all that and jumped at the chance to prove his theories right. He travelled to Cairo in 1011 to survey the task. Though the Pharaoh Menes, around 3000 BC, built many canals and desired to dam the Nile, no one had attempted such an undertaking until Caliph Hakim ordered Ibn al-Haytham to do so.
Ibn al-Haytham must have known that this monumental assignment would probably take the rest of his life. But the forty-seven-year-old philosopher and scientist probably did not suspect that it would cost him his life, or might do. But once he had met Hakim and started work it became increasingly obvious that turning down the job would result in his becoming another of Hakim’s victims.
When he arrived in Egypt Hakim was so excited at the news that he rushed to the village of Khandaq to meet Ibn al-Haytham in person. Ibn al-Haytham, who was lodging there in a small caravanserai, was on his way to Cairo. The mad Caliph was so pleased with Ibn al-Haytham’s plans that he pledged his entire treasury to complete the project.
Somewhat unnerved by his sponsor’s intensity, Ibn al-Haytham now began the long task of travelling up the Nile to find the right place to make the dam. He found it at Janadil, a village near Aswan. As they passed the Pyramids and great temples along the way Ibn al-Haytham began to get his first feelings of disquiet. He remarked on the astonishing precision and workmanship and drew the worrying conclusion that these incredible engineers, who could build the highest buildings in the world, had chosen not to dam the Nile. There must have been a reason.
At Janadil Ibn al-Haytham saw that the high granite banks would be perfect for a dam. Then he measured the opening, which owing to the disparity between the actual river banks and the granite cliffs, looked less than it was. The banks were only 1,800 feet apart. Only. But the granite was 3,200 feet apart at ground level. At a point 360 feet above the river, the granite cliffs were 12,000 feet apart. More than two miles. Sixteen times the width of the Great Pyramid.
Unfortunately he was 900 years too early. He’d found the right spot, and years later this was where the Aswan dam was built.
When Ibn al-Haytham finished his measuring he knew he was in deep trouble. Without any form of mechanical assistance he’d need a million men to complete the dam, and even then it would take one or two hundred years. It would be folly to continue. It would be folly to return.
Reluctantly he travelled to Cairo to break the news to Hakim. If Ibn al-Haytham expected to be reprimanded, punished or even killed he was wrong. Hakim, as unpredictable as ever, offered him a plum job as an adviser in his inner court. Ibn al-Haytham accepted, again out of fear. He knew about such tactics. You lull a man into a false sense of security, you invite him into your tent and shazam – you strangle him with the silken cord of his own dressing gown. The Caliph Hakim was, Ibn al-Haytham now saw, a sly man, a feared man. Sooner or later he would turn on Ibn al-Haytham, the man who had said he could dam the Nile and didn’t.
Ibn al-Haytham then pulled a master stroke out of the bag. He pretended to be mad.
Now, convincing a mad monarch that you are madder than he is takes some doing. The genuinely mad are very often gifted with a sixth sense for sniffing out the genuinely sane. It would have to be a class act. So Ibn al-Haytham went overboard: he ate foul beans off the floor – which he had placed in a bucket to look like nightsoil. He refused to answer questions except by singing answers. He insisted on wearing a mask when he left the house. He claimed it was the mask that did his talking as he had lost that power.
The ruse worked, kind of. Hakim had him removed from government and there was no question of Ibn al-Haytham being executed for failing to dam the Nile. Under Islamic law the insane have a protected status, they are untouchable. However, Hakim still had his suspicions, so he imprisoned Ibn al-Haytham in two rooms in Cairo for months, months that stretched into years. Strangely this may have been exactly the chance the scholar needed.
Imprisoned in his darkened rooms, Ibn al-Haytham began to think about light and vision. He invented the camera obscura – not surprisingly he felt as if he were trapped within one – and the camera obscura is the basis of all cameras that ever followed. He devised the first scientific thought experiments – because he had no chance of testing things in practice. He was the first to realise that the ancient Greeks were wrong about sight – we do not send out rays from our eyes that see things. Rather, light reflects off objects and that makes them visible. That he was imprisoned is obvious from his science: of the dozens of experiments he describes, only one requires the use of an assistant.
So, Ibn al-Haytham, imprisoned in Cairo for failing to dam the Nile, had much time to contemplate not just the scientific but also the mundane, the mystical and the plain insane. He pondered deeply on how to rid the world of the benighted evil of Hakim.
2 • Hakim goes out too much
Islam arrived as a stranger and will depart as a stranger.
Hadith of the Prophet Muhammad
The power behind the Egyptian throne at that time was not a man but Sitt al-Mulk, ‘the lady of power’. We will see that she was not the first or last female ruler of Egypt. Her brother, and the reason she was able to rule at all, was the mad Caliph Hakim. His rule was so bad that she was welcomed as an alternative. Compared to his excesses, a woman was no madness at all.
Hakim started his problematic rule by going out too much. This was something no caliph should do, unless wearing a workable disguise. Hakim, on one memorable Saturday, made no fewer than six appearances. One on horseback, one riding a donkey, a third in a litter hoisted on high by a retinue of Nubian porters. At the fourth appearance he was seen on the Nile in a boat not wearing a turban. After this disgrace the fifth and sixth appearances almost failed to register.
Hakim was only eleven when his forty-two-year-old father died in the bath, as a result of taking dangerous medication after a freak accident (his foot had slipped off a carriage wheel and been twisted and snapped by the rotating spokes – he was in the process of whipping a servant at the time). It was hot weather and the body of the old Caliph needed to be buried. Hakim’s father, like Hakim himself when he grew up, was a very tall man and it is reported that no coffin would fit him. He was carried to his grave in a box with the end knocked out and his bare feet poking out.
Hakim’s sister, Sitt al-Mulk, who was sixteen years his senior, found her brother increasingly intolerable. He was obsessed with her apparent infidelities. And he hated the sound of barking dogs. There have always bee
n stray dogs – the earliest travellers record their presence as something unpleasant but inevitable. But so terrified of Hakim were the people that they vied to complete the order for the dogs’ destruction. One breed was rendered extinct. If a dog appeared at the head of an alley, day or night, it would be chased down and killed, stoned or beaten to death immediately. To try and kill them all, which Hakim nearly managed, shows just how insane he was.
People were terrified of his random malignancies. Hakim once walked past a butcher’s shop, took a liking to the enormous cleaver stuck in a block, pulled it out and swung at the astonished butcher, cutting his head in two. He then carried on with his ramble through the city as if nothing had happened, holding the dripping cleaver by his side. Onlookers were so stunned that the butcher remained unburied, lying in his shop until three days later Hakim ordered a magnificent shroud to be sent to cover his putrefying remains.
Hakim developed a preference for nocturnal walks around the city. Dressed in sumptuous clothes, bejewelled and wrapped in furs in winter, he and his retinue demanded that the shops be open at all hours of the night when they chose to visit them. The city became inured to this reversal of ordinary life. Indeed, as any modern visitor to Cairo will attest during the month of Ramadan, Cairenes adjust very easily to living by night. But once the city had become addicted to living at night Hakim changed his mind and decreed that no one should appear on the streets between dusk and dawn. All public amusements were banned. Wine, even for Christians, was forbidden. Gallons of wine were tipped into the Nile at Roda, turning it as red as blood. The entire grape crop was also dumped in the river, where it fermented at the bank, turning the Nile briefly into a river of alcohol. Even mulukhiyya, a national dish, was made illegal. (This would be like banning something like potato crisps in the UK.) Then Hakim ordered that no women should appear on the streets. Christians were forced to wear a heavy wooden cross at all times, Jews a tiny bell around their necks to warn of their arrival. Donkeys rather than horses were to be ridden by those of these religions – and this despite the Islamic ruling that Christians and Jews as ‘People of the Book’ were entitled to protection under the Caliphate.
The final descent into madness, and its resolution, were caused by the Nile itself. A persistent drought had meant food shortages. Hakim called forth his advisers and rebuked them for failing to solve the problem of the drought. Bread prices rose as grain grew ever scarcer. Bread is a sensitive issue to all Egyptians. There were bread riots in the 1970s that almost toppled Sadat. Hakim decided to tax it in order to dissuade people from buying too much. Instead the people revolted and bread riots spread through the city. It was a merciful release from all the restrictions they had been labouring under.
The increasingly lonely and ascetic Hakim took to wandering in a simple woollen robe among the hills of Moqattam. One day he disappeared. His sister ordered the hills from Moqattam to Helwan to be combed and all they found was a donkey with its leg gashed. It was said that this beast belonged to the mad Caliph. It was clear, to most Cairenes, that his sister, who would go on to rule for the next four years (using her infant nephew as a proxy and excuse), had killed Hakim. Allowing her to rule was not a problem. Hakim had been so hated that the person – man or woman – who removed him deserved to rule.
Yet Sitt al-Mulk had seemed genuinely upset by her brother’s death. Rumours abounded about how he had really died. It was claimed the real killer was a member of the Beni Husayn tribe who had killed the Caliph with three other men. This man was captured and interrogated. ‘This is how I did it,’ he announced, shoving a previously hidden stiletto blade between his own ribs and dying in front of his inquisitors.
3 • The strange confession of Ibn al-Haytham
One does not learn fully from one’s host by remaining a guest.
Ethiopian proverb
‘For ten years I have been under house arrest. It has been a fruitful time for me but I grew weary of the solitude. My single window, from which I could see the palace and the Moqattam Hills behind, was my sole joy for many months. The light that entered through this window was life to me. When the light ceased it was as if I were dead. The fellow who brought my food, and later his son, were contemptuous of me at first. I was known as the madman. But they brought me paper and ink, I was allowed to work. Using shadows cast by various engines and contrivances I made I was able to calculate all the distances outside my window. I knew, for example, that the Caliph left from a door 560 cubits from my window. That he passed under an arch on his nocturnal visits to the Moqattam at exactly 879 cubits. That he entered a cave exactly 17,987 cubits from the arch. This last was discovered by the warder’s son who became my unwitting accomplice. I am getting ahead of myself. First I needed to demonstrate my use to them. I was mad, yes, but I had the power of seeing into the future, the power of curing all ills. The boy suffered from a partially severed finger. The stench of it was appalling but sheer ignorance and fear allowed the infected digit to remain, hanging on by little more than a thread of skin. He began to sicken and I saw that infection would set in and he would die. The father agreed to hold the boy down. I severed the finger using a barber’s razor cleansed in a flame. Then I applied a poultice of honey and myrrh. The hand, and the boy, recovered quickly and I was now their physician. I took care to treat only the obviously curable. If they brought a relative who would be impossible to improve I would go into a trance, roll my eyes and pronounce them incompatible with my peculiar talents. Over time I had sufficiently few of such cases to win their trust – knowing that many of those I cured were going to get better anyway.
‘The warder’s son, on my instructions, paced out the required distances into the Moqattam Hills and left two polished flat-bottomed pots at locations I informed him of. When the sun was high the reflections off these pots could be calculated as angles with a quadrant device I fashioned. I instructed the boy to scatter lentils across the paths at regular distances beyond the copper pots. Each day he reported whether the lines of lentils had been disturbed. Quite soon I obtained a detailed account of where my former lord and master took himself off to in the lonely hills. There were rumours he belonged to a strange sect who promised power in the other world . . . It was no concern of mine. I was busy at the time constructing light boxes that contained one or more candles. With these I proved that light beams that are separated by holes in a screen do not merge when they cross over. Light must therefore be composed of particles of some sort that interact, but not in the way, for example, particles of a liquid interact.
‘I adapted one of these boxes so that a precisely directed sunray could be captured by a curved mirror and then ignite a candle into flame. Here I drew on the experiments written about in my book On parabolic burning mirrors. This sun-powered device was placed in the wilderness, its position noted on the quadrant. I ought to say that the area of the hills his majesty entered was always checked and emptied of people by a squadron of his trusted troops. My royal tormentor would, when his troops had gone, then head towards the cave of his sect of fellow idiots. This place was lit by a single flickering candle which served like the lighthouse in Alexandria, to draw him in. With my device located on the opposite side of a perilous ravine I waited for a moonless night. Reflecting the rays of the setting sun with a mirror, I directed a light stream at the capturing mirror in the device. I kept my burning mirror still, using a heavy blacksmith’s vice that held the quadrant with the mirror attached. I had to trust that the candle was now alight, though, as it was still daylight, I could not tell.
‘The sun set in layers of glowing yellow and red, making the hills look wonderfully wholesome. The squadron were completing their inspection. Night fell. Yes! I could see my little candle flickering, some way ahead of the second candle that indicated the cave. I knew, though, that the second candle would not be visible until it was a little too late.
‘The following morning the blood-stained clothes of the Caliph Hakim were found at the bottom of the rocky wadi. He had fallen
and his body was taken away by whoever wished to profit by such a manoeuvre. In my own case I was released a few days later and took ship to Basra without further incident.’
The disappearance of Hakim, who was missed by very few, caused great consternation nevertheless. A caliph, God’s representative on earth, does not just disappear. The conundrum led to one of the major tenets of a religion still with us today. The Druze are the remnant cult of those who believe that Hakim will return. They had been formed from an Ismaili sect by an itinerant astrologer who had wormed his way into the confidence of the mad Caliph. Hamza ibn Ali told Hakim what he most wanted to hear: that he would never die because he was actually God himself. In a mystical sense this might have been true, but Hamza went one further and announced that Hakim would one day return in person, a statement that qualified him in the eyes of the Cairene populace as being just as mad as Hakim. The Druze were driven out of Egypt for their unorthodox views, finally taking up their current residence in the mountains of Lebanon.
4 • Ibn al-Haytham and the student
The road and an argument end when one wants them to end.
Nubian proverb
Ibn al-Haytham was free to get home to Basra, which he did. In his later years all the knowledge of his scientific exploits joined with the years of contemplation: he became known as a wise man, someone to be consulted, someone from whom one could learn what life was really about. It was said that by talking to Ibn al-Haytham one’s best course in life would be revealed twenty years earlier than if one relied on the natural abrasions of life experience. If you listened, he could save you time.
Naturally this made him popular. He took measures to be hard to reach and sometimes did his old trick of acting mad to dissuade the unsuitable from bothering him for advice they would never take. But some, a minority, he was able to help.
Red Nile: The Biography of the World’s Greatest River Page 17