"Alkali... ?" The geometer frowned.

"Sodium carbonate would do nicely. Hm. That's making it worse, isn't it? How to describe it... let me think. It would be bitter to the taste, very soluble in water, turns red wine blue. Fizzes in vinegar. Can be boiled with fats and oils to make soap..."

"Oh! Of course! Natron! We use it in embalming. It helps desiccate the corpse. But how would you use natron in your ship?"

"Simple. During wake-periods on my ship, my lungs give off a waste gas, which we call carbon dioxide. It can become toxic if allowed to reach high concentrations. The alkali absorbs it."

"Well then, I think the next step is to gather up these things and take them out to your ship. I'll call the servants. No-I can't. They're all down in the city, celebrating the New Year. You and I and Ne-tiy will have to do it."

"It's just as well. Less risk to the ship."

To the extent that any of the geometer's aplomb had left him, very nearly all of it had by now returned. He said, "As you may have read in my mind, it is the practice for one of our Library clerks to go through every incoming ship to look for new books to copy. I wonder..."

"Ah, my friend. I have dozens of books, none in any Earth-language. The Maintenance of Ion Drives... Collecting on Airless Worlds... Operation of the Sleep Casket. Some with holos, for which you'd need a laser reader. But I

tell you what. You like maps. Before I finally leave, I'll give you a sort of map."

"Fair enough."

An hour later Khor, Eratosthenes, and Ne-tiy had wound the last of the linen strips around the hydraulic tubes, refilled the depleted oil surge tank, and secured the amphora of natron in the storage locker.

"The balsam resin will require a couple of hours to cure and harden," said Eratosthenes. "And I am due at Ptolemy's palace very soon. May I suggest that you join me?"

"Won't I excite comment?"

"Hm. You're a bit taller than average. However, just keep covered with your body cape. I'll tell Ptolemy you're a foreign visitor and your religion requires the covering."

"Is it an offense to you, my host, that I conceal my body from you in this way?"

The Cyrenian smiled. "Since you are my guest, it pleases me that you do as you see fit." He bowed. "This way to the chariot."

11. Ptolemy on His Balcony

On this night of the summer solstice, the beginning of the three weeks of madness celebrating the rising of the river. Ptolemy the Second, called Philadelphus, stood on his balcony and looked out over the royal harbor. Shading his eyes, he could barely make out the tiny light swinging in slow arcs in the blackness. At his request, the captain had fixed the lantern at the top of the mast of the royal barge. Why? No reason given. He had simply said, do it, and it was done. Actually, it was a token of a promise to himself: tomorrow he would be on that ship, headed south on the Nile, with all concerns of state receding sternward.

For five thousand years the rulers of Egypt had made this trip. Tradition held that when the sun ceased his northward journey, pharaoh would set forth, sailing all the way to Thebes, to ensure a proper flood. If pharaoh did not thus set forth on the bosom of Hapi, the river would not rise. If the river did not rise, there would be no sowing, and no harvest. Famine would grip the land. The tax gatherers would gather little or nothing. The army could not be paid. The dynasty could fall.

Superst.i.tious nonsense?

Who was he to say?

It was best to go along with it. Anyhow, he always looked forward to the long trip on the river. He just wished Arsinoe' were still alive.

Noises in the streets below brought his eyes down to the parade of dancing torches. The annual infection had spread even here, to the guarded serenity of the royal quarter. In a way it was unsettling; yet on the whole it was rea.s.suring that the people were content to stay within their multi-millennial rut. No riots, no revolutions, no marches against the granaries. Not this week, anyhow. Let the beer flow!

He looked around as a woman in an elegant linen dress and cape parted the hangings and stepped out to join him. A thick black wig, artfully dusted with gold powder, fell to her shoulders. She was his concubine of the month. Her name was Pauni, daughter of a n.o.ble house. He named them for the current Egyptian month. It was the only way he could attach names to their beautiful faces. And so it had been, since the death of Arsinoe, his true sister-wife, twenty years ago. By Greek ideas, that marriage had been incest; but it was quite in the pharaonic tradition. A bit of irony: in the river tongue, the word for concubine was "sne-t," which meant "sister."

(Ah, Arsinoe, Arsinoe. I loved you greatly. You should not have died. It was the only unkind thing you ever did.)

"Respect their traditions. Respect their religion. Worship their G.o.ds," his great father Ptolemy, Alexander's general, had told him. "Be pious. You lose nothing, and you will preserve the dynasty." He took the woman by the arm and they listened in silence to the revelry. "The old man was right," he muttered.

"Who, my lord?" said Pauni politely.

"My father. When the Persians conquered Egypt, they flouted the local religions. Ochus, the satrap, killed the sacred bull. The priests invoked a terrible curse on him, and on his masters in Persepolis. And so Alexander came, and destroyed Persia. He came to Egypt, and gave all honor to the priests. He sacrificed to Apis and other native G.o.ds. He made the great journey across the desert, without road or path, to the sanctuary of Ammon at Siwah. There the priests declared his divine descent, and that he was indeed the son of Ammon." He reflected. "Did I ever tell you about Alexander's trip across the desert to Siwah?"

(Several times, my lord.) "No, sire, I don't recall that you did."

"Ah. Well, then. The storms had destroyed the roads. Even the guides were lost. The sun was pitiless, and the men were dropping from heat stroke. But trie G.o.ds sent a great flock of ravens, who flew in circles overhead, and shaded Alexander. And if the guides made a wrong turn, the birds screamed until they went straight again."

"Amazing," said Pauni.

The royal Greek sighed again. If only he didn't owe so much money to so many people. The Jews had helped him- and his father-finance the great light tower on Pharos. It had been finished these nine years, and the treasury was still paying. And the Egyptian priests. The public debt was soaring because of their demands for new temples. And then there was the standing army, all mercenaries, and they liked to be paid regularly, in hard clanking bra.s.s. And the navy. A thousand years ago Rameses had not been troubled with ships that sailed the Great Green. And two thousand years ago the pharaohs didn't even use money. There wasn't any. It hadn't been invented yet. Go, said Khufu to his peasants. Build me a tomb-pyramid. One million men, working twenty years. And they had done it, and not an obol paid out to anyone. Alas, how things had changed. "Who rules Egypt?" he mused softly. "Do I? No. Do the one million Greeks who have settled here? No. Well, then, do the priests and their seven million fellahin? Or is the land a hopeless anarchy?"

By now she was used to this. "Speaking of priests," Pauni reminded him gently, "the high priest of Horus is here. Also Rabbi Ben Shem. And then the other notables: Eratosthenes and his lady. The geometer brings a very strange guest, who covers his body with a long black veil. And then there are the consuls and amba.s.sadors-Claudius Pulcher the Roman, Ha-milcar Barca, the Carthaginian..."

Ptolemy suppressed a groan. Eratosthenes. He had tried to forget him, but of course it was impossible. The man of measures was going to make his report tonight. And what will you say, n.o.ble philosopher? How big is the world? As to that, say anything you like. But the shape! Declare Earth a flat square, or a disc, or a cylinder. Any of these. But you know you must not say "sphere" or "ball" or "globe." That's heresy, mathematician. Don't betray me, my brother Greek.

There is a long line waiting to take your place as curator of the great Library. And it isn't just me you should worry about. If you say "sphere," the local holies will have you floating in the ca.n.a.l before the night is out.

He paused. The girl looked up at him in grave concern. He thought: she knows I am fifty-nine, and that I am dying. Ah, to be young again. No, don't turn back. Let it be finally done. Nothing really matters very much anymore. From here on in, let us have peace. He smiled. "Perhaps we should rejoin our guests.''

12. Heresy

A little cl.u.s.ter had already formed around the two amba.s.sadors. The Carthaginian was explaining something: "One of my purposes here is to obtain copies of the world map of Eratosthenes."

"And what good is that?" growled Claudius Pulcher, the Roman.

"Carthage will probably win our present war with Rome, n.o.ble amba.s.sador. If so, we will expand into Spain and Gaul. For that we will need good maps. If we lose-may Baal save us!-we will certainly need to recoup our fortunes, and we would look to western Europe for that. Again we would need good maps. Including-" (here he gave the stolid Pulcher a crafty leer) "a good showing of the pa.s.ses through the Alps."

"Pa.s.ses... ?"

"For our war elephants."

The Roman genera! stared at him blankly. Then recognition dawned. "Oh-you mean from Gaul, over the mountains into Italy." He began to laugh. He laughed so hard he spilled his wine. "Excuse me." He walked back to the credentia for a refill.

Ptolemy watched him for a moment, then turned back to the Carthaginian. "The great Alexander was always fearful of war elephants. He never really discovered how to cope with them. Quite an idea, Hamilcar Barca."

"But there's still a problem," said Eratosthenes. "We have several reports by travelers in the Library. They all say the pa.s.ses are very narrow, barely wide enough for a horse. How will you get your elephants through?"

"You should read more of your own books, learned scroll-master," said Barca. "The mountains are made of calx.

Vinegar dissolves calx. We shall bring hundreds of casks of vinegar. The mountains shall melt away, and the great war beasts shall pa.s.s."

"Why does Carthage disclose its strategy to Rome in advance?" asked Ptolemy.

The young Carthaginian grinned. "No harm in it at all. First, they think we lie, that we try to deceive them. Therefore, they won't bother to defend the pa.s.ses. Second, they're so confident that if and when they do fortify the pa.s.ses they would so tell us. Third, they are incapable of thinking in terms of empire for themselves, so they can't conceive that their enemies would have such impossible ideas. They lack imagination. They don't know what dreams are."

"They seem to have done very well despite these deficiencies," demurred Eratosthenes. "Three hundred years ago they were just a fishing village on the Tiber. Now they rule the entire Italic peninsula. Who needs dreams?"