N.B. This is a fictionalized account – see author's note below
In the hush just before fajr, before the devout gather to greet the sunrise with prayers towards Mecca, the Scholar emerges from a fitful sleep and confronts the darkness. He remembers, as consciousness returns, that he is a prisoner in his own home. There is nothing to alleviate the mind-numbing sameness of days, no friendly voice or warm touch to keep the suffocating isolation at bay – not even the musty comfort of his books. Truly, I am cursed among men.
This is not how he envisioned his future as an ambitious young man back in Basra. There, he devoured the works of Aristotle and dreamed of scientific pursuits. "The ink of the scholar is more holy than the blood of the martyrs," the Koran says, and he believed it. So he followed the throngs of Basran fortune-seekers to Cairo, home to the Dar al-'llm ("House of Knowledge"), and found lodgings near the Azhar Mosque. He taught in the mosque's school, and worked as a scribe in the Dar al-'llm, copying Arabic translations of Euclid, Ptolemy and his beloved Aristotle, being careful not to smudge the pages with ink-stained fingers. All the knowledge in the world was at his fingertips. Yet the wisdom of the Ancients could not help him to foresee the ill fortune about to befall him.
One day he received a summons from Cairo's reigning Caliph, al-Hakim bi-Amr Allah – a tremendous honour for a humble scribe. The Scholar felt small and insignificant as he passed through the palace gates into a large courtyard ringed by stone archways; twin minarets cast their shadows over a reflecting pool. He was even more cowed by the majesty of the blue-domed throne room – its stucco walls dotted with bright mosaic tiles. Even the Caliph seemed dwarfed by the setting, despite his robes of state and jewelled turban.
The Caliph was most eager to find a man who could solve a perplexing problem, he explained, and the Scholar came highly recommended. Every year, the flooding of the Nile served as a harbinger for the end of summer, and an omen for that year's harvest. Too much flooding, and the crops would be destroyed; too little, and drought and famine would ravage the land. His people were utterly dependent on the fickle whims of the great river for their survival. Man's ingenuity had already produced watermills to grind grain, and water-raising machines. If men could control water in this way, could they not also build a dam to control the flooding and bend the Nile to the Caliph's will?
The Scholar was flattered by the Caliph's attentions, and tempted by the promise of riches and fame should he succeed. Silencing the doubt in his mind, he told al-Hakim "It can be done." And the Caliph appointed him head engineer of the project. But when the Scholar arrived at the proposed site, a cold dread ran through him, despite the dry heat of the desert: the sheer scale of the river and valley were beyond imagination. How could anything control such a force of nature? With a sick feeling he drew up detailed plans for the dam's construction, made measurements, devised various schemes and tested inventions. But the scale of the engineering needed was beyond even the vast resources of the Caliph. In the end, he realized that it could not be done. He had failed.
The prospect of facing the Caliph with this news filled the Scholar with dread. People whispered that al-Hakim had once disembowelled a horseman in his service with a spear just outside the gates of the mosque. An abusive grocer turned muhtasib had his tongue and hands cut off before being summarily executed, and a corrupt judge was beheaded and burned for illegally seizing 20,000 dinars from a young man's inheritance. Even minor infractions were met with arrests, stiff fines or beatings, if not death. Yet al-Hakim was not without compassion: once, after brutally beheading a man, he relented a few days later and ordered the body to be exhumed for proper burial and funeral rites.
The Scholar had heard the stories, and he feared the worst.
As he made his way back to his lodgings along the narrow winding streets of Cairo, he had a heavy heart, anxiety building with every step. He passed a beggar, noting the torn garments, tangled hair smeared with faeces, the jerky motions and staccato outbursts – all the hallmarks of a confused mind. He paused to drink from a public fountain and caught a glimpse of his own reflection in the water. He looked very much like that lunatic beggar: bedraggled, smelly, with unkempt hair and an unruly beard from his months camped out in the field, haunted eyes set deep in a face drawn taut with worry.
And then the Scholar had an epiphany. Would not the Caliph show mercy to a madman?
His fellow scribes at the Dar al-'llm thought it might just work when he told them of his plan, and they agreed to help. He locked himself in his home and resisted the urge to bathe, while they spread rumours that his mind had snapped under the strain of trying to tame the mighty Nile. The gossip soon reached the Caliph, and he summoned the Scholar to gauge for himself the mental state of his engineer.
Heart pounding, the Scholar shambled into the throne room, doing his best to mimic the beggar's behaviour – rocking and muttering to himself, even pulling out tufts of hair in only half-feigned agitation. His friends swore that he had been in this state for weeks, and they feared he would not recover. If the Caliph's physicians who examined him suspected the pretence, they did not betray him. They told al-Hakim his engineer had, indeed, gone mad, and recommended confining the stricken Scholar to his home.
Mercurial he may have been, but the Caliph was no fool. "I see," he murmured when his physicians gave their verdict. Eyes narrowed, hands clasped behind his back, he slowly circled the Scholar, coldly assessing the man with the supposed broken mind cringing on the ground before him. He wrinkled his nose at the stench.
"Very well," he said at last. "He shall be placed under house arrest until further notice. But his worldly goods shall be forfeited."
"Yes, yes, of course, a small price to pay." The Scholar's friends kissed the hem of the Caliph's robes in relief, bowing repeatedly as they backed towards the door with the newly diagnosed lunatic between them.
"Wait." Al-Hakim held up a hand, and guards promptly blocked their exit. "Confiscate his books, too." He smiled slyly. "After all, what use does a madman have for reading?"
And so the Scholar escaped with his life, but not his freedom – a forgotten man leading a solitary life. No books, no visitors – no distractions to fill the hours. Al-Hakim chose the punishment well; it could drive a sane man mad. Each day, the Scholar counts the hours until night, when he can lose himself in slumber. He always awakens too soon.
Now, many moons later, as the merchants noisily make their way to the marketplace to set up their wares, he watches the first light of dawn stream through the bedchamber door and finds himself wondering how that light can reach him in the darkness. If only I had my books. The Scholar sighs, itching to feel the crisp pages between his fingers. He ponders what he recalls from the Ancients. Aristotle wrote of mysterious "forms" travelling from objects into the eye, while Euclid and Ptolemy proclaimed that the eye emits rays of light that strike and illuminate surrounding objects.
Yet when lying alone in his darkened room, no light shines forth from the Scholar's eyes to illuminate the bare walls before him. He sees nothing until sunrise. There is a window high above the archway to his bedchamber, on the eastern wall. The sunlight streams through the window and reflects off the western wall directly across from the archway, sending that reflected light back through the opening to provide faint illumination in his bedchamber. As the morning light grows stronger, so does the light reflecting into his bedchamber.
Is it possible that the Ancients were mistaken? This is an audacious thought – who is he to question Aristotle? But then he conceives an alternative explanation. Perhaps light radiates in many different straight lines, from every point of a luminous object, travelling in every direction at once. We only "see" objects that reflect those rays of light that enter the eye.
The Scholar decides to put his theory to the test. He lacks his books, but he has lamps and candles; screens and wooden blocks; tubes and makeshift rulers, and a sheet of thin copper. He has paper and ink. And not even al-Hakim has the power to take away his senses, or his mind. I can still be a Scholar.
First, he gazes through a tube at objects in the room, using a ruler to measure the line of sight. He can only "see" an object when it stands directly in front of the tube's opening. Then he covers part of the opening. Now, he can only see that part of the object that is opposite the uncovered part of the tube.
His excitement mounting, the Scholar next punches a large round hole in a sheet of copper and inserts a tube that is open at one end and closed at the other, save for a pinhole the width of a needle. He holds a candle flame to the open end and places an urn in front of the pinhole at the other. Only a little light from the flame travels through the pinhole to the urn; the copper sheet blocks the rest. Then he moves the candle, and the light cast upon the urn looks different. When just the tip of the flame is in front of the pinhole, only a little light falls on the urn; when the centre of the flame is in front of the pinhole, more light falls on the urn. But there is always some light that reaches the urn; it must radiate from each point of the fire.
There is no mysterious "form" that all objects emit, nor do our eyes emit rays of light so we can see. Instead, there are sources of primary light – the Sun or a candle's flame – and this light is reflected from other objects (secondary light) and passes into our eyes so that we can perceive them. So Aristotle was wrong about light and vision. So were Euclid and Ptolemy. And if such great minds could be wrong about this, they might be wrong about other supposed "truths" as well!
Never again will the Scholar blindly accept assertions made by the Ancients, however revered; he vows to test and question everything. I will make myself the enemy of all I have read, attack the old ideas from every angle and dismantle all that do not pass my tests until only the truth remains.
Now the Scholar's days and nights are filled with activity. He studies how curved mirrors and glass bend and warp the light. He places lamps at different points around his bedchamber, all facing a single pinhole in the wall, and observes how the light from each lamp appears as a distinct spot on the far wall in the darkened room next door. He screens one lamp, then another, and notes how just the spot from the screened lamp disappears from the wall next door when he does so.
The outside world fades as he works with increasingly feverish intensity, oblivious to the sounds of city life echoing in the streets beyond his stone walls. Days turn into weeks, then months, then years, as he painstakingly records the details of all he discovers. There are seven volumes by the time he is done – a unified theory of light and vision that cites not a single ancient authority. He calls his manuscript Kitab al-Manazir (Book of Optics).
A decade has passed. One morning the Scholar hears a knock on his door. No-one knocks at his door – the guards leave food, water and other necessities, but have never interacted with him. He opens the door to al-Hakim's vizier, a servant by his side. The three men stand in awkward silence, the servant shifting nervously from one foot to the other, eyes fixed resolutely on the ground. The vizier clears his throat.
"Our Caliph is missing," he says. Lately, he explained, al-Hakim had taken to riding out into the al-Muqattam hills at night to fast and meditate. "Alas – this time, he has not returned."
Only his bloodstained robes and donkey had been found. There are whispers of foul play, of assassins hired by al-Hakim's half-sister, Sitt al-Mulk, so that she can rule as regent until the Caliph's young son comes of age. But there is no proof of such a plot, and little choice but to declare al-Hakim dead.
The vizier studies the Scholar for a moment, then pulls a scroll from his robes. "This is a decree by the court physicians that the curse of madness is no longer upon you. Your house arrest is lifted. You are free to go."
He snaps his fingers and turns to leave with his servant, pausing at the door to glance back at the Scholar. "May Allah smile upon you," the vizier murmurs. And he is gone.
The Scholar stands trembling in the cool shadows. Could it be true? He takes a shuffling step towards the door, then another. No guard tries to stop him. In the bright bustle of dhuhr, as the Sun reaches its zenith and the devout kneel for their noontime prayers, he emerges from his prison, blinking in the sudden glare, as if awakening from an unpleasant dream. He tilts his head back, raises his palms, and embraces the light.
This is a work of fiction – a fanciful re-imagining of a 10-year period in the life of the medieval Muslim polymath Ibn al-Haytham (AD 965–1040) considered by many historians to be the father of modern optics. Living at the height of the golden age of Arabic science, al-Haytham developed an early version of the scientific method 200 years before scholars in Western Europe, and is most celebrated for the seven-volume Kitab al-Manazir (Book of Optics). The first three books deal with visual perception and psychology, while the remaining volumes focus on physical optics. It is frequently ranked alongside Newton's Principia as one of the most influential books in physics.
Very little is known about al-Haytham, other than what is contained in his written works – those that survived the pillaging of the Crusades in the 11th century and the sacking of Baghdad in the mid-13th century, which effectively ended the golden age. This story is inspired by historical accounts, but I have taken some liberties for the sake of the narrative. For instance, accounts differ as to whether al-Haytham was placed under house arrest or imprisoned in an asylum; I have opted for the former.
It is likely that al-Haytham did fail to build a dam to regulate the flooding of the Nile, at a site near the modern Aswan Dam, and feigned madness to escape execution by the Caliph al-Hakim of the Fatimid dynasty. He wrote the Book of Optics during this period, although details of the exact conditions under which he worked are lacking. There really was a House of Knowledge, and visitors to Cairo can still visit the Azhur Mosque where he taught. Al-Haytham went on to make contributions to astronomy, mathematics, engineering, medicine and physics. The year 2011 marks the millennial celebration of the Book of Optics.