Another tendril of an image was drowned in the present. What the senses tell us can overwhelm all else, and that is good, but sometimes I could wish otherwise. Or was it relief I felt? Confused, I stepped away from the others. Looking around at the ice beams poking out of that stark landscape I was struck by the strangeness of it, and I sank to the floor, slipping through the gravel as if I didn’t exist, as if I were the holo and the ground were real. The sense of the room left me entirely and for a moment I was on Pluto, on an almost transparent Pluto where you could sit unsuited, and breathe cool air, and stare at a megalith more silent and enigmatic than any pointing at Earth’s sky. Awe — so rare, so longed for — so much like its cousin terror, when it does flood the mind. And it was the edge of deep fear that brought the elusive memory crashing out of presque vu into consciousness: the moor by the sea, a thumbnail crescent of moon, Madeleine’s round face full of pity. I scrambled to my feet, frightened and excited. My trip to Earth — images from it were strung like algae in filaments, one led me to the next immediately. My nerves jangled and my blood spurted through me, and Pluto and Mars alike vanished.

I was holding my temples in my hand when the lights came up, and I am afraid my colleagues saw me in that pose and thought me mad. I barely noticed; I made some excuse to Nguyen and Stallworth, and stumbled out of the center into the surprising light of a clear afternoon.

Lemniscate islands — in the outflow channels these knobs of rock harder than their surroundings were scoured into their characteristic shape by the catastrophic floods that carved the channels.

I remember I spent the trip to Earth in the centrifuge, working out in terran gravity to prepare myself for landfall. My third wife Maggie had just left me; she hadn’t wanted me to make the trip. I didn’t want the marriage to end. We had children, my habits were firm. Nothing would have tempted me to break them but a voyage to Earth. The Committee hated anyone going, but I got the chance and I left, feeling utterly depressed, a whole life shattered behind me. Again I was in an interregnum, stripped of habits, painfully alive.

Quickly I took new habits, grew a new exfoliation. The voyage itself was a life, and I remember it all of a piece. I worked out every day until my body no longer felt like a backpack weighing me down; it was still heavy, but I could carry it. Every day I worked on those machines until I was too tired to think.

There was a woman there doing the same work, though her motives were less negative. She worked to make her lungs pump like bellows, her skin pop sweat at every pore. She attacked the machines with brio, and laughed at my grimness. Have you tried this machine? she would ask. That one? I would shake my head and try them. She only talked about workouts, and I liked that. Her name was Madeleine. She was about my age — one hundred or so. Of her appearance I recall only a mass of thick dark blond hair, tied back in the centrifuge, let free in the commons, where it drew my eye always. And she was strong.

But it didn’t occur to me that I was falling in love. How could I be? I was tired, sick of love, too drained ever to feel it again. How many times could it happen, after all? Wasn’t love another finite power of ours, that would run out like water from an aquifer? And Madeleine was so distanced (but I liked that). So we talked for hours as we worked out. She taught me to jump rope. We traded our stories. She had helped to organize the tour, and had been to Earth twice before. And every day we worked until we collapsed, in the “air soup” of Earth. Perhaps that soup does something to the brain. Because I could feel it happening again, no matter what I commanded myself to think. It’s frightening how helplessly people are themselves! We think, “I understand myself, I will change, I will take control, I will protect myself,” and then in any kind of stress we behave with exactly the same character we were born with, the character beneath the “I.” So I fell in love helplessly, as if catching a disease.

And Madeline liked me. I pumped weights until I could be pleased with my body, and I avoided looking in the centrifuge mirrors, where my red cheeks and stiff black hair would have mocked me. Too bad you can’t work out on your face. (Vanity is slow to die; even past two hundred, when our faces resemble turtles’, we value them as great maps of experience, histories of emotional lives. And at this time I was only a hundred, and looked very young.)

The memory exists in small linked cells, like diatoms of algae in a filament; next diatom: stepping out of a shuttle onto a desert floor, our group like a croud of Columbuses. Despite my workouts I felt heavy, and the blazing sun stunned me. It seemed the sky burned. And the blue — that color doesn’t exist on Mars, but I felt that there was a part of my brain that was made to recognize sky blue.

Brief images of our tour: Madeleine led me up trails from Macchu Pichu; we laughed at the solemn statues of Easter Island; a tour guide deferred to my knowledge of some site or other. Though I felt a dreamlike recognition for Earth’s ruins from my years of study, I still clumped around as wide-eyed and rubber-necked as the rest of our group. We looked like asteroid miners in Burroughs, I am sure.

Bigger diatom: at Angkor Wat one evening, Madeleine and I crawled over the crumbling temples under smeary twinkling stars. Standing on a vine-covered roof in the twilit jungle I saw a look I knew on her face. Just as I embraced her to kiss her a bug the size of my fist buzzed between our faces. We leapt back — “My God!” — stumbled on vines, laughed. “What was that?”

I don’t know,” Madeleine said, “but it sure was ugly!”

“You’re not kidding! A dragonfly?”

“You’ve got me.” We looked about warily. “Hope there aren’t more.”

“Me too.”

“Sure glad there aren’t any big bugs like that on Mars.”

“Me too. Pretty scary bug, all right,”

And we laughed. That was the embrace. A few minutes later she said, “But we can’t do it out here. We might get attacked by bugs!” And we went back to her room at the hotel.

And in Persepolis, one sharp image: as I strode over the hectares of strewn marble like Tamburlaine, euphoric with the raw impact of the past, she said to me, “You make it new.”

But in Florence we joined another group, from the university in Hellas, and their guide and Madeleine were old friends. Wasn’t that how it happened? They took off together into the city. Why not? Jealousy, what foolishness. Perhaps I am less able than most people to control my emotions. Florence reminded me of Burroughs, with the yellowing stone and the river running down the crease in the hills, and all the bridges. I walked the narrow streets with a marble pedestal in my stomach that almost bowed me over. The fierce sun beat on me in pulses and burned my neck, and I could hardly breathe in the thick wet air. Madeleine and her friend appeared in an alley, searching for local ice cream. I got sick of all the beggars and sat in my room at the hotel listening to the cutting melancholy of the “Souvenir of Florence.” I forgot the Etruscans, the Renaissance; all I cared for was the feeling in that sextet. You can make unhappiness into an aesthetic experience, and everyone tries to, so there must be something to it; but I don’t think it does much good. It only means you will remember it better, because of the coding in objective correlatives. It doesn’t make you less unhappy.

Well, it was stupid of me. I admit that.

Last diatom, the largest — the one remembered in the holo chamber we visited the Orkney Islands north of Britain, to see the passage graves and the stone rings of Stenness and Brodgar. The islands were abandoned, and a rime of frost covered the ground in the mornings, as it was early winter. I insisted that Madeleine take a dawn walk with me, over the heath to Stenness ring. The land we crossed looked almost Martian. I told her that I loved her, she said I didn’t know her well enough to say such a thing. As if knowledge had anything to do with love. “You know what I mean,” I said.