"Acrophilia," I said.

"True. Baptizing a thing doesn't explain it, though. I never understood why I did it. Still don't, for that matter. I did finally stop it for a long while, though. Middle-age hormone shift perhaps. Who knows? Then I came here to teach. It was when I heard of your own activities that I began thinking about it again. This led to the desire, the act, the return of the compulsion. It has been with me ever since. I've spent more time wondering why people quit climbing things than why they start."

"It does seem the natural thing to do."

"Exactly."

He took another drink, offered me one. I would have liked to but I know my limits, and sitting there on the ledge, I was not about to push them. So he gestured with the bottle, skyward, then: "To the lady with the smile," he said, and drank it for me.

"To the rocks of empire," he added a moment later, with a swing and a swig to another starry sector. The wrong one, but no matter. He knew as well as I that it was still below the horizon.

He settled back, found a cigar, lit it, mused: "How many eyes per head, I wonder, in the place they regard the ‘Mona Lisa'? Are they faceted? Fixed? And of what color?"

"Only two. You know that. And sort of hazel-in the pictures, anyway."

"Must you deflate romantic rhetoric? Besides, the Astabigans have plenty of visitors from other worlds who will be viewing her."

"True. And for that matter, the British Crown Jewels are in the custody of people with crescent-shaped pupils. Kind of lavender-eyed, I believe."

"Sufficient," he said. "Redeeming. Thank you."

A shooting star burned its way earthward. My cigarette butt followed it.

"I wonder if it was a fair trade?" he said. "We don't understand the Rhennius machine, and even the aliens aren't certain what the star-stone represents."

"It wasn't exactly a trade."

"Two of the treasures of Earth are gone and we have a couple of theirs in return. What else would you call it?"

"A link in a kula chain," I said.

"I am not familiar with the term. Tell me about it."

"The parallel struck me as I read the details of the deal we had been offered. The kula is a kind of ceremonial voyage undertaken at various times by the inhabitants of the island groups to the east of New Guinea-the Trobriand Islanders, the Papuans of Melanesia. It is a sort of double circuit, a movement in two opposite directions among the islands. The purpose is the mutual exchange of articles having no special functional value to the various tribes involved, but possessed of great cultural significance. Generally, they are body ornaments-necklaces, bracelets-bearing names and colorful histories. They move slowly about the great circuit of the islands, accompanied by their ever-growing histories, are exchanged with considerable pomp and ceremony and serve to focus cultural enthusiasm in a way that promotes a certain unity, a sense of mutual obligation and trust. Now, the general similarity to the exchange program we are entering with the aliens seems pretty obvious. The objects become both cultural hostages and emblems of honor to the trustees. By their existence, their circulation, their display, they inevitably create something of a community feeling. This is the true purpose of a kula chain, as I see it. That's why I didn't like the word ‘trade.' "

"Most interesting. None of the reports I've heard or read put it in that light-and certainly none of them compared it to the kula phenomenon. They cast it more in terms of an initiation fee for joining the galactic club, the price of admission to enjoy the benefits of trade and the exchange of ideas. That sort of thing."

"That was just the sales pitch, to ease public protest over the relinquishment of cultural treasures. All we were really promised was reciprocity in the chain. I'm sure those other things will eventually come to pass, but not necessarily as a direct result. No. Our governments were indulging in the time-honored practice of giving the people a simple, palatable explanation of a complex thing."

"I can see that," he said, and he stretched and yawned. "In. fact, I prefer your interpretation over the official one."

I lit another cigarette.

"Thanks," I said. "I feel obligated to point out, though, that I have always been a sucker for ideas I find aesthetically pleasing. The cosmic sweep of the thing-an interstellar kula chain-affirming the differences and at the same time emphasizing the similarities of all the intelligent races in the galaxy-tying them together, building common traditions ... The notion strikes me as kind of fine."

"Obviously," he said, gesturing then toward the higher stages of the cathedral. "Tell me, are you going to climb the rest of the way up tonight?"

"Probably, in a little while. Did you want to go now?"

"No, no. I was just curious. You generally go all the way to the top, don't you?"

"Yes. Don't you?"

"Not always. In fact, I've recently been keeping more to the middle heights. The reason I asked, though, is that I have a question, seeing that you are in a philosophical mood."

"It's catching."

"All right. Then tell me what it feels like when you reach the top."

"An elation, I guess. A sense of accomplishment, sort of."

"Up here the view is less obstructed. You can see farther, take in more of the features of the landscape. Is that it, I wonder? A better perspective?"

"Part of it, maybe. But there is always one other thing I feel when I reach the top: I always want to go just a little bit higher, and I always feel that I almost can, that I am just about to."

"Yes. That's true," he said.

"Why do you ask?"

"I don't know. To be reminded, perhaps. That boy in Cambridge would have said the same thing you did, but I had partly forgotten. It is not just the world that has changed."

He took another drink.

"I wonder," he said, "what it was really like? That first encounter-out there-with the aliens. Hard to believe that several years have passed since it happened. The governments obviously glossed up the story, so we will probably never know exactly what was said or done. A coincidental run-in, neither of us familiar with the system where we met. Exploring, that's all. It was doubtless less of a shock to them, being acquainted with so many other races across the galaxy. Still ... I remember that unexpected return. Mission accomplished. A half century ahead of schedule. Accompanied by an Astabigan scouting vessel. If an object attains the speed of light it turns into a pumpkin. Everybody knew that. But the aliens had found a way of cheating space out of its pumpkins, and they brought our ship back through the tunnel they made under it. Or across the bridge over it. Or something like that. Lots of business for the math department. Strange feeling. Not at all the way I had thought it might be. Sort of like working your way up a steeple or a dome-really difficult going-and then, when you reach the point where you realize you've got it made, you look up and see that someone else is already there on top. So we'd run into a galactic civilization-a loose confederation of races that's been in existence for millennia. Maybe we were lucky. It could easily have taken a couple more centuries. Maybe not, though. My feelings were, and still are, mixed. How can you go a little bit higher after something that anticlimactic? They've given us the technical know-how to build pumpkin-proof ships of our own. They've also warned us off a lot of celestial real estate. They've granted us a place in their exchange program, where we're bound to make a poor showing. Changes will be coming faster and faster in the years ahead. The world may even begin to change at a noticeable rate. What then? Once that petty-pace quality is lost, everyone may wind up as bewildered as a drunken old nightclimber on a cathedral who has been vouchsafed a glimpse of the clicking gear teeth between himself here and the towers of Cambridge there, wherever. What then? See the mainspring and turn to pumpkins? Retire? Alkaid, Mizar, Alioth, Megrez, Phecda, Merak and Dubhe ... They have been there. They know them. Perhaps, deep down inside, I wanted us to be alone in the cosmos-to claim all of that for ourselves. Or any aliens encountered, a little behind us in everything. Greedy, proud, selfish ... True. Now, though, we're the provincials, God help us! Enough left to drink to our health. Good! Here's to it! I spit into the face of Time that has transfigured me!"