“Betelgeuse,” she says. She grins, and it is suddenly lighter in the hall. I did not know it was dark before. The dark was there first, but the light caught up. “Rigel. Antares. Light and all colors. Wavelengths…” Her hands ripple in the air, and I know she means the pattern that wavelength and frequency make.

“Binaries,” I say. “Brown dwarfs.”

Her face twists and relaxes. “Oh, that’s old,” she says. “Chu and Sanderly have reclassified a lot of those—” She stops. “Lou— I thought you spent all your time with normals. Playing normal.”

“I go to church,” I say. “I go to fencing club.”

“Fencing?”

“Swords,” I say. Her worried look does not change. “It’s… a kind of game,” I say. “We try to poke each other.”

“Why?” She still looks puzzled. “If you like stars—”

“I like fencing, too,” I say.

“With normal people,” she says.

“Yes, I like them.”

“It’s hard…” she says. “I go to the planetarium. I try to talk to the scientists who come, but… the words tangle. I can tell they do not want to talk to me. They act like I am stupid or crazy.”

“The people I know, they are not too bad,” I say. I feel guilty as I say it, because Marjory is more than “not too bad.” Tom and Lucia are better than “not too bad.” “Except for the one who tried to kill me.”

“Tried to kill you?” Linda says. I am surprised that she did not know but remember that I never told her. Maybe she does not watch the news.

“He was angry with me,” I say.

“Because you are autistic?”

“Not exactly… well… yes.” What was the core of Don’s anger, after all, but the fact that I, a mere incomplete, a false-person, was succeeding in his world?

“That is sick,” Linda says, with emphasis. She gives a great shrug and turns away. “Stars,” she says.

I go into my office, thinking of light and dark and stars and the space between them that is full of light they pour out. How can there be any dark in space with all the stars in it? If we can see the stars, that means there is light. And our instruments that see other than visible light, they detect it in a great blur — it is everywhere.

I do not understand why people speak of space as cold and dark, unwelcoming. It is as if they never went out in the night and looked up. Wherever real dark is, it is beyond the range of our instruments, far on the edge of the universe, where dark came first. But the light catches up.

Before I was born, people thought even more wrong things about autistic children. I have read about it. Darker than dark.

I did not know Linda liked stars. I did not know she wanted to work in astronomy. Maybe she even wanted to go into space, the way I did. Do. Do still. If the treatment works, maybe I can — the very thought holds me motionless, frozen in delight, and then I have to move. I stand up and stretch, but it is not enough.

Eric is just getting off the trampoline as I come into the gym. He has been bouncing to Beethoven’s Fifth Symphony, but it is too strong for what I want to think about. Eric nods at me, and I change the music, scrolling through the possibilities until something feels right. Carmen. The orchestral suite. Yes.

I need that excitement. I need that explosive quality. I bounce higher and higher, feeling the wonderful openness of free fall before I feel the equally wonderful compression, joints squeezing, muscles working to push me to a higher bounce. Opposites are the same thing in different directions. Action and reaction. Gravity — I do not know an opposite for gravity, but the elasticity of the trampoline creates one. Numbers and patterns race through my mind, forming, breaking up, re-forming.

I remember being afraid of water, the unstable, unpredictable shifts and wobbles in it as it touched me. I remember the explosive joy of finally swimming, the realization that even though it was unstable, even though I could not predict the changing pressure in the pool, I could still stay afloat and move in the direction I chose to go. I remember being afraid of the bicycle, of its wobbly unpredictability, and the same joy when I figured out how to ride out that unpredictability, how to use my will to overcome its innate chaos. Again I am afraid, more afraid because I understand more — I could lose all the adaptations I have made and have nothing — but if I can ride this wave, this biological bicycle, then I will have incomparably more.

As my legs tire, I bounce lower, lower, lower, and finally stop.

They do not want us stupid and helpless. They do not want to destroy our minds; they want to use them.

I do not want to be used. I want to use my own mind, myself, for what I want to do.

I think I may want to try this treatment. I do not have to. I do not need to: I am all right as I am. But I think I am beginning to want to because maybe, if I change, and if it is my idea and not theirs, then maybe I can learn what I want to learn and do what I want to do. It is not any one thing; it is all the things at once, all the possibilities. “I will not be the same,” I say, letting go of the comfortable gravity, flying up out of that certainly into the uncertainty of free fall.

When I walk out, I feel light in both ways, still in less than normal gravity and still full of more light than darkness. But gravity returns when I think of telling my friends what I am doing. I think they will not like it any better than the Center’s lawyer.

Mr. Aldrin comes by to tell us that the company will not agree to provide LifeTime treatments at this time, though they may — he emphasizes that it is only a possibility — assist those of us who want to have LifeTime treatments after the other treatment, if it is successful. “It is too dangerous to do them together,” he says. “It increases the risk, and then if something does go wrong it would last longer.”

I think he should say it plainly: if the treatment causes more damage, we would be worse off and the company would have to support us for longer. But I know that normal people do not say things plainly.

We do not talk among ourselves after he leaves. The others all look at me, but they do not say anything. I hope Linda takes the treatment anyway. I want to talk to her more about stars and gravity and the speed of light and dark.

In my own office, I call Ms. Beasley at Legal Aid and tell her that I have decided to agree to the treatment. She asks me if I am sure. I am not sure, but I am sure enough. Then I call Mr. Aldrin and tell him. He also asks if I am sure. “Yes,” I say, and then I ask, “Is your brother going to do it?” I have been wondering about his brother.

“Jeremy?” He sounds surprised that I asked. I think it is a reasonable question. “I don’t know, Lou. It depends on the size of the group. If they open it up to outsiders, I’ll consider asking him. If he could live on his own, if he could be happier…”

“He is not happy?” I ask.

Mr. Aldrin sighs. “I… don’t talk about him much,” he says. I wait. Not talking about something much does not mean someone doesn’t want to talk about it. Mr. Aldrin clears his throat and then goes on. “No, Lou, he’s not happy. He’s… very impaired. The doctors then… my parents… he’s on a lot of medication, and he never learned to talk very well.” I think I understand what he is not saying. His brother was born too early, before the treatments that helped me and the others. Maybe he didn’t get the best treatment, even of those available at the time. I think of the descriptions in the books; I imagine Jeremy being stuck where I was as a young child.

“I hope the new treatment works,” I say. “I hope it works for him, too.”

Mr. Aldrin makes a sound I do not understand; his voice is hoarse when he speaks again. “Thank you, Lou,” he says. “You’re — you’re a good man.”