The eye was blue and white, with a white eyebrow and a dark pupil. White of cloud, blue of distance. As if it were part of the sky itself.

"Louis!" Teela screamed. "Do something!"

It isn't happening, Louis told himself. His throat was a column of solid ice. His mind ran about in his skull like something trapped. It's a big universe, but some things really are impossible.

"Louis!"

Louis found his voice. "Speaker. Hey, Speaker. What do you see?"

The kzin took his time answering. His voice was curiously flat. "I see a great human eye ahead of us."

"Human?"

"Yes. Do you see it too?"

The word Louis would never have used made all the difference. Human. A human eye. If the eye were a supernatural manifestation, then a kzin should see a kzinti eye, or nothing at all.

"Then it's natural," Louis told himself. "It has to be."

Teela looked at him hopefully.

But how was it drawing them toward itself?

"Oh," said Louis Wu. He moved the steering handle hard right. The 'cycles curved away to spinward.

"This is not our route," Speaker said instantly. "Louis, bring us back. Or put the fleet under my command."

"You aren't thinking of going through that thing, are you?"

"It is too large to go around."

"Speaker, it's no bigger than Plato crater. We can circle it in an hour. Why take chances?"

"If you are afraid, drop out of formation, Louis. Circle the eye and meet me on the other side. Teela, you may do the same. I will go through."

"Why?" Louis's voice sounded ragged even to him. "Do you think that — accidental cloud formation is a challenge to your manhood?"

"My what? Louis, my ability to procreate is not at issue. My courage is."

"Why?"

The 'cycles fell across the sky at cruising velocity, twelve hundred miles per hour.

"Why is your courage at issue? You owe me an answer. You're risking our lives."

"No. You may go around the Eye."

"And how do we find you afterward?"

The kzin considered. "I concede the point. Have you heard of the Kdapt-Preacher heresy?"

"No."

"In the dark days that followed the Fourth Truce with Man, Mad Kdapt-Preacher headed a new religion. He was executed by the Patriarch himself in single combat, since he bore a partial name, but his heretical religion survives in secret to this day. Kdapt-Preacher believed that God the Creator made man in his own image."

"Man? But — Kdapt-Preacher was a kzin?"

Yes. You kept winning, Louis. For three centuries and four wars you had been winning. Kdapt's disciples ware masks of human skin when they prayed. They hoped to confuse the Creator long enough to win a war."

"And when you saw that eye peering over the horizon at us -"

"Yes."

"Oh, boy."

"I put it to you, Louis, that my own theory is more likely than yours. An accidental cloud formation. Really, Louis!"

Louis's brain was working again. "Strike accidental. Maybe the Ring engineers set up the Eye formation for their own amusement, or as a pointer to something."

"To what?"

"Who knows? Something big. An amusement park, a major church. The headquarters of the Optometrist's Union. With the techniques they had, and the room, it might be anything!"

"A prison for Peeping Toms," said Teela, suddenly getting into the spirit of the thing. "A university for private detectives! A test pattern on a giant tridee set! I was as scared as you were, Speaker." Teela sounded normal again. "I thought it was — I don't know what I thought. But I'm with you. We'll go through together."

"Very well, Teela."

"If he blinks, we'll both be killed."

"'The majority is always sane,'" Louis quoted. "I'm going to call Nessus."

"Finagle, yes! He must have gone through it already, or around it!"

Louis laughed harder than he ordinarily would have. He had been very frightened. "You don't think Nessus is breaking trail for us, do you?"

"Huh?"

"He's a puppeteer. He circled around behind us, then he probably slaved his 'cycle to Speaker's. That way Speaker can't catch him, and any danger he's likely to meet, we'll meet first."

Speaker said, "You have a remarkable ability to think like a coward, Louis."

"Don't knock it. We're on an alien world. We need alien insights."

"Very well, call him since you and he seem to think so much alike. I intend to face the Eye, and learn what lies behind it, or within it."

Louis called Nessus.

In the intercom image, only the puppeteer's back was visible. His mane stirred slowly with his breathing.

"Nessus," Louis called. Then, louder, "Nessus!"

The puppeteer twitched. A triangular head rose in enquiry.

"I was afraid I'd have to use the siren."

"Is there an emergency?" Both heads came up, quiveringly alert.

Louis was finding it impossible to return the vast blue stare ahead of him. His eyes kept sliding away. He said, "A kind of emergency. My crazy team are about to wreck themselves. I don't think we can afford to lose them."

"Explain, please."

"Look ahead of you and tell me if you can see a cloud formation in the shape of a human eye."

"I see it," said the puppeteer.

"Any idea what's causing it?"

"Obviously it is a storm of some kind. You will already have reasoned that there will be no spiral hurricane formations on the Ringworld."

"Oh!" Louis hadn't even wondered about that.

"The spiral form of a hurricane derives from coriolis force, from the difference in the velocities of two air masses at different latitudes. A planet is a rotating spheroid. If two masses of air move toward each other to fill a partial vacuum, one moving north and the other south, their residual velocities will carry them past each other. Thus a whirlpool of air is formed."

"I know what causes hurricanes."

"Then you must realize that on the Ringworld, all contiguous masses of air have virtually the same velocity. There will be no whirlpool effect."

Louis looked ahead of him toward the eye-shaped storm. "But what kind of a storm would you get? None at all, I'd think. You wouldn't get any circulation of air at all."

"Untrue, Louis. Hot air would rise, cold air would sink. But these effects could not produce such a storm as that ahead of us."

"Too right."

"What is Speaker threatening to do?"

"Fly through the center of that Finagle-sired thing, with Teela loyally following after him."

The puppeteer whistled a tone as pure and beautiful as ruby laser light "That seems dangerous. The sonic folds would protect them against the ravages of any ordinary storm. But this looks to be no ordinary storm."

"I was thinking that it might be artificial."

"Yes … The Ringworlders would have set up their own Ring-girdling circulation system. But that system would have stopped working when the Ring power supply failed. I don't see … ah. I have it, Louis."

"What is it?"

"We must postulate an air-sink, a region where air disappears near the middle of the storm. All the rest follows.

"Consider. The air sink creates a partial vacuum. Air masses flow in from spinward and antispinward -"

"And port and starboard."

"These we can ignore," the puppeteer said crisply. "But air moving in from spinward win become fractionally lighter than the surrounding air. It will rise. Air moving in from the opposite direction, from antispinward, will become fractionally heavier — -"

Louis was groping with an improperly visualized picture. "Why?"

"From antispinward it comes, Louis. Its rotational velocity is increased fractionally with respect to the Ring. Centrifugal force causes it to sink slightly.

"It forms the lower eyelid of the eye. The air from spinward, rising, forms the upper eyelid. There is a whirlpool effect, surely, but the axis of the whirlpool is horizontal, where on a planet it would be vertical."