1Three hundred years went by. Rome fell and was forgotten. In the desert of Arabia a prophet arose, and his people carried their faith from the ocean in the west to the borders of China, faster than any people had ever carried anything.
2They built a new city on the river Tigris. It was round, like a shield laid on the ground, with four gates looking four ways, and they called it the City of Peace. Others called it Baghdad.
3Now the rulers of that city did a thing that conquerors seldom do. They looked at the peoples they had conquered, the Persians and the Syrians and the Egyptians and the people of Sind, and they asked: "What did you know?"
4In the days of the caliph al-Ma'mun there was a house in Baghdad where that question was asked every day. It was called the House of Wisdom. The caliph filled it with books and with men who could read them, and he did not ask what a man believed before he asked what a man could read.
5There was a copyist in that house named Yuhanna. He was nineteen, a Christian from the old town of al-Hira, and he had Syriac from his mother, Arabic from the street, and Greek from the priests. He was the least of all who worked there. He ruled lines and mixed ink.
6One spring it was told in the house that the caliph had written to the emperor of the Romans, his enemy, to ask not for gold or cities but for old books. And the emperor, after some thought, had said yes. Men were chosen to cross the mountains and fetch them. They needed someone to carry the ink and check the Greek, someone who would not be missed. They took Yuhanna.
7They went up the river and across the plain and into the mountains called Taurus, by the narrow pass where two laden mules cannot walk abreast. On one side of that pass men prayed toward Mecca and on the other they prayed toward Jerusalem, and each summer they raided each other, and had done for two hundred years.
8In the cities of the Romans the envoys were given books, and they bought more, and by autumn the mules were loaded. But the chief of the envoys wanted one book above the others, and had not found a whole copy of it. It was the great book of the stars, made long ago in Alexandria by the star-counter Ptolemy. The Greeks called it the Great Gathering. The Arabs, hearing the Greek, called it simply the Greatest.
9On the road home a monk told them of a house of brothers high in the hills, two days off the road, that had a chest of old books no one had opened in a lifetime. The chief of the envoys looked at the sky, which was the colour of iron. He had the caliph's mules to think of. He would not go.
10"Send the boy," said the guide. "If he is back in four days we will wait at the mouth of the pass. If he is not, the snow will have decided."
11So Yuhanna went up alone, on a borrowed mule, with a purse of the caliph's silver sewn into his belt.
12The house of the brothers was nine men and a goat. They were kind to him. They gave him barley soup, and they showed him the chest, and it was nearly empty.
13"We had more," said the abbot, without shame. "But skins are dear, brother, and the old books were only numbers and pagan fables. We needed a psalter. One cannot sing to God from an empty page."
14He took Yuhanna to the writing room. And there Yuhanna saw a thing that he dreamed of for the rest of his life. An old brother sat at a slanted board with a knife and a lump of pumice. Under his hands lay a great page of calfskin, covered in small brown Greek and in circles within circles. The old brother was scraping it clean. Half the page was already white. Where it was white, the first lines of a psalm had been written in fresh black ink.
15On the floor beside him lay the rest of the book, unbound, in a heap. Yuhanna knelt and turned the leaves over. He saw the table of strings across the circle. He saw the names of the wandering stars. It was the Greatest, and thirty leaves of it were already psalms.
16Do not think badly of the brothers. They were poor men, and they wished to praise God, and they were using what they had. They did not know what it was. That is the whole of it. Most of what has been lost in this world was not burned by enemies. It was scraped clean by honest people who needed the skin.
17"Father," said Yuhanna, and his voice was not steady, "how much is a psalter's worth of new skin?"
18The abbot named a price. It was more than the house had seen in ten years.
19Yuhanna cut the belt from his waist with the old brother's own knife and poured the caliph's silver onto the writing board. "Buy skins for ten psalters," he said. "And give me that heap on the floor."
20They wrapped the leaves in oiled goat-hide and tied them to his back. The brothers blessed him at the gate. He came down the mountain a day late, and at the mouth of the pass there was no one. There were the black rings of three fires and the tracks of many mules, going south and already filling.
21The snow had decided.
22He went into the pass alone. On the first day the mule fell on ice and broke its leg, and he had to leave it. On the second day he walked. He had bread for one day. The wind came down the pass so hard that he went from rock to rock, holding on, like a man crossing a river.
23That night he found a shepherd's hut with no roof. He had flint and he had nothing to burn. He sat against the wall with the book on his knees and he knew quite plainly that a man could live until morning if he had a fire, and that he was holding two hundred leaves of dry calfskin.
24He took the bundle from his back. He undid one knot. Then he sat with his hand on it for a long time.
25He thought of the old brother's knife. He thought: the brother wanted a psalm, and I want to be warm. What is the difference between us? And he could find only one. The brother did not know.
26He tied the knot again. He put the book inside his coat, against his chest, and wrapped his arms around it, and sang every psalm he knew in Syriac to keep from sleeping. He knew a great many.
27At first light, horsemen came up the pass from the south. They were Arab raiders of the frontier, going home late. They found a young man sitting in a hut with white feet, singing in a tongue they did not know, and they would have ridden on. But he called out to them in Arabic, "I am the caliph's man, and I carry the caliph's book!" and that was strange enough to stop them.
28They tied him on a horse. He lost two toes of his left foot, and he walked with a stick ever after. He came into Baghdad in the last week of winter, by the Syrian gate, with the book against his chest.
29Now hear what he found there. He had thought he would be met as a hero. He was met by a quarrel. The House of Wisdom was in an uproar over a single word.
30A Greek book of healing was being put into Arabic. No one in the house could do it in one step. So a Christian read the Greek aloud and said it in Syriac; and a Persian who had been raised in the old faith of the fire took the Syriac and said it in Arabic; and a Muslim from Basra, who knew no Greek at all but knew his own tongue like a jeweller knows stones, wrote the Arabic down and made it sing.
31The Greek word was a name for a sickness. There was no such word in Arabic. The Christian wanted to carry the Greek word over whole. The Persian wanted a Persian word. The man from Basra said that God had given the Arabs a language that lacked nothing, and he would find the word if they would be quiet. They were not quiet.
32Then the call to prayer sounded over the round city. The man from Basra put down his pen, and he and the other Muslims rose and went out to pray. The Christian took out a small worn book and moved his lips over it by the window. The Persian sat with his eyes closed and his hands open on his knees.
33After a little while they all came back to the table, and took up the same word, and went on shouting at each other about it as if they had never stopped.
34Yuhanna stood in the doorway on his stick and watched this. He had come through the snow from a country where men of two faiths killed each other every summer in a mountain pass. And here men of three faiths were fighting like brothers over what to call a fever, so that a physician not yet born could cure a child not yet born, who might be of any faith at all.
35When they unwrapped his bundle and saw what it was, the quarrel ended. The chief of the envoys, who had left him in the pass, kissed him on both cheeks and wept. It was the best copy any of them had seen. It lacked only the thirty leaves that had become psalms, and those they found afterward in another book.
36The man who came most often to study the leaves was a quiet reckoner from the far country of Khwarazm, beyond the Oxus. His name was Muhammad son of Musa, called al-Khwarizmi. He was a devout man, and he began every piece of work with the praise of God. He was making tables of the stars for the caliph, and he wanted the table of strings.
37Yuhanna, who had nearly died for that table, watched him copy it out. And he saw that the man was not writing in letter-numbers as the Greeks did, nor in Arabic letters as the clerks did. He was writing in strange small signs, nine of them, and here and there a little circle.
38"What is that?" said Yuhanna.
39"The reckoning of the Indians," said al-Khwarizmi. "A man came from Sind to the court of the caliph's great-grandfather, with a book of the stars from his own country. The numbers in it were written so. Nine signs. Each takes its worth from the place where it stands."
40"And the circle?"
41"The circle keeps the place when the place is empty. So that the rows do not close up, and thirty is not taken for three." He smiled. "It is the most useful nothing in the world. I am writing a small book to teach it. A child can learn it in a week."
42There was another book the reckoner was making. The caliph himself had asked for it. It was not for star-counters. It was for judges and merchants and the men who dig canals: a book to show how a thing not known can be found from the things that are known.
43A man dies and leaves a debt, two sons, a widow, and a gift promised to a stranger. What is each one's share? A field is to be cut in three by a line. Where does the line go? In every city of the caliph's lands such questions were settled by shouting, or by whoever had the stronger cousins.
44Al-Khwarizmi showed how to settle them by a road of small sure steps, the same steps every time, that anyone could walk. You set the unknown thing on one side like a weight in a scale. You take from both sides alike, and add to both sides alike, until the scale stands level and the unknown thing stands alone. For the chief of these steps he used the bone-setter's word, the word for putting back what was broken. Al-jabr. Restoring.
45Now there was in that city a market that had not been in any city before it. It was the street of the paper-sellers.
46Paper had come from the east. The makers of it, it was told, were men of China taken captive in a battle on the far frontier, and they taught the craft in Samarkand, and from Samarkand it came down the long road to Baghdad. It was made of rags and old rope, beaten in water. It cost almost nothing.
47Within a year, the Greatest had been put into Arabic, and within three years there were copies of it on paper in that street. Yuhanna used to walk there in the evenings on his stick. He would find one on a stall and open it, and look at the table of strings in its new clothing, and close it again and say nothing to the seller.
48He had sat in the snow with his hand on the knot. Now there were forty of it. A man would have to burn the whole city to burn them all, and some had already gone out by the four gates, to Damascus, to Egypt, to places he would never see.
49He had a friend in the house in those years, a young Arab of good family named al-Kindi, who read everything and feared nothing. There were people in the city who said that the books of the Greeks were foreign and pagan and should be left alone. Al-Kindi answered them in a book of his own, some years after. He wrote:
50"We ought not to be ashamed of appreciating the truth and of acquiring it wherever it comes from, even if it comes from races distant and nations different from us."
51Yuhanna copied that sentence out and kept it folded in his psalter. He lived to be old. He ruled a great many lines. And once, when he was old, a Greek monk came through Baghdad on his way to the holy places, and Yuhanna gave him a gift for the brothers in the hills: a psalter on clean new paper, and with it a book of the stars, in Greek, copied whole, with nothing scraped away.
52"Tell them it is only numbers," he said. "Tell them to keep it anyway."