So how fortunate it was that I had this tablet, and a place in which to view it. It gave me something to act on—something, that is, besides Fraa Spelikon’s throat. If I worked on it hard enough and were lucky, perhaps I could come up with some result that I could announce one evening in the Refectory to the humiliation of Spelikon, Trestanas, and Statho. Then I could storm out of the concent in disgust before they had time to Throw me Back.

And in the meantime, studying this thing answered that need in my gut to take some kind of action in response to what had been inflicted on Orolo. And I’d found that taking such action was the only way to transmute my anger back into grief. And when I was grieving—instead of angry—young fids no longer shied away from me, and my mind was no longer filled with images of blood pumping from Fraa Spelikon’s severed arteries.

So I had no choice but to put Sammann and the dust cover out of my mind, and concentrate instead on what Clesthyra’s Eye had seen during the night-time. I had kept track of the weather those seventy-seven nights. More than half had been cloudy. There had only been seventeen nights of really clear seeing.

Once I allowed my eyes to adjust to the darkness, it was easy to find north on this thing, because it was the pole around which all the stars revolved. If the image was frozen, or playing back at something like normal speed, the stars appeared as stationary points of light. But if I sped up the playback, each star, with the exception of the pole star, traced an arc centered on the pole as Arbre rotated beneath it. Our fancier telescopes had polar axis systems, driven by the clock, that eliminated this problem. These telescopes rotated “backwards” at the same speed as Arbre rotated “forwards” so that the stars remained stationary above them. Clesthyra’s Eye was not so equipped.

The tablet could be commanded to tell what it had seen in several different ways. To this point I’d been using it like a speelycaptor with its play, pause, and fast-forward buttons. But it could do things that speelycaptors couldn’t, such as integrate an image over a span of time. This was an echo of the Praxic Age when, instead of tablets like this one, cosmographers had used plates coated with chemicals sensitive to light. Because many of the things they looked at were so faint, they had often needed to expose those plates for hours at a time. A photomnemonic tablet worked both ways. If you were to “play back” such a record in speelycaptor mode, you might see nothing more than a few stars and a bit of haze, but if you configured the tablet to show the still image integrated over time, a spiral galaxy or nebula might pop out.

So my first experiment was to select a night that had been clear, and configure the tablet to integrate all the light that Clesthyra’s Eye had taken in that night into a single still image. The first results weren’t very good because I set the start time too early and the stop time too late, so everything was washed out by the brightness in the sky after dusk and before dawn. But after making some adjustments I was able to get the image I wanted.

It was a black disk etched with thousands of fine concentric arcs, each of which was the track made by a particular star or planet as Arbre spun beneath it. This image was crisscrossed by several red dotted lines and brilliant white streaks: the traces made by the lights of aerocraft passing across our sky. The ones in the center, made by high-flying craft, ran nearly straight. Over toward one edge the star-field was all but obliterated by a sheaf of fat white curves: craft coming in to land at the local aerodrome, all following more or less the same glide path.

Only one thing in this whole firmament did not move: the pole star. If our hypothesis was correct as to what Fraa Orolo had been looking for—namely, something in a polar orbit—then, assuming it was bright enough to be seen on this thing, it ought to register as a streak passing near the pole star. It would be straight or nearly so, and oriented at right angles to the myriad arcs made by the stars—it would move north-south as they moved east-west.

Not only that, but such a satellite should make more than one such streak on a given night. Jesry and I had worked it out. A satellite in a low orbit should make a complete pass around Arbre in about an hour and a half. If it made a streak on the tablet as it passed over the pole at, say, midnight, then at about one-thirty it should make another streak, and another at three, and another at four-thirty. It should always stay in the same plane with respect to the fixed stars. But during each of those ninety-minute intervals Arbre would rotate through twenty-two and a half degrees of longitude. And so the successive streaks that a given satellite made should not be drawn on top of each other. Instead they should be separated by angles of about twenty-two and a half degrees (or pi/8 as theoricians measured angles). They should look like cuts on a pie.

My work on that first day in the sub-cellar consisted of making the tablet produce a time exposure for the first clear night, then zooming in on the vicinity of the pole star and looking for something that resembled a pie-cutting diagram. I succeeded in this so easily that I was almost disappointed. Because there was more than one such satellite, what it looked like was more complex:

But if I looked at it long enough I could see it as several different pie-cut diagrams piled on top of each other.

“It’s an anticlimax,” I told Jesry at supper. We had somehow managed to avoid Barb and sit together in a corner of the Refectory.

“Again?”

“I’d sort of thought that if I could see anything at all in a polar orbit, that’d be the end of it. Mystery solved, case closed. But it is not so. There are several satellites in polar orbits. Probably have been ever since the Praxic Age. Old ones wear out and fall down. The Panjandrums launch new ones.”

“That is not a new result,” he pointed out. “If you go out at night and stand facing north and wait long enough, you can see those things hurtling over the pole with the naked eye.”

I chewed a bit of food as I struggled to master the urge to punch him in the nose. But this was how things were done in theorics. It wasn’t only the Lorites who said that is not a new result. People reinvented the wheel all the time. There was nothing shameful in it. If the rest of us oohed and aahed and said, “Gosh, a wheel, no one’s ever thought of that before,” just to make that person feel good, nothing would ever get done. But still it stung to risk so much and do so much work to get a result, only to be told it was nothing new.

“I don’t claim it is a new result,” I told him, with elaborate patience. “I’m only letting you know what happened the first time I was able to spend a couple of hours with the tablet. And I guess I am posing a question.”

“All right. What is the question?”

“Fraa Orolo must have known that there were several satellites in polar orbits and that this wasn’t a big deal. To a cosmographer, it’s no more remarkable than aerocraft flying overhead.”

“An annoyance. A distraction,” Jesry said, nodding.

“So what was it that he risked Anathem to see?”

“He didn’t just risk Anathem. He—”

I waved him off. “You know what I mean. This is no time to go Kefedokhles.”

Jesry gazed into space above my left shoulder. Most others would have been embarrassed or irritated by my remark. Not him! He couldn’t care less. How I envied him! “We know that he needed a speelycaptor to see it,” Jesry said. “The naked eye wasn’t good enough.”

“He had to see all of this in a different way. He couldn’t make time exposures on a tablet,” I put in.