I sensed someone beside me, and turned uneasily—I was still young, and this was a city and totally new to me. The girl standing there was someone I recognized only slightly. She sat behind me in one of my classes; I’d noticed in passing her thick plastic glasses. She was pudgy, doughy in the way some little girls are, and she wore her hair in pigtails, with thick overgrown bangs hiding her forehead. She was my age, I knew, but she looked like a little girl in every way except one. She had a small scar like a tiny star on her cheek, and this gave her a sophisticated look, as though it were a beauty mark. I took all this in, the way I took everything in, saving it all for some later moment when I’d have time to analyze and make meaning out of what I’d seen.

“You want to go in?” she said, nodding at the river.

“No,” I said.

“Come on. Let’s get closer.”

We crossed the bridge and scrambled down its edge and made our way through the thick growth of jewelweed and knotweed growing there. We scrambled to the very edge of the water, and stood together looking at the cold reflections of the city.

“I don’t think we better,” I said finally. “I don’t think it’s supposed to be very clean.”

We heard the sound of the river lapping against its shore. We heard the city all around us, the gentle roar of cars.

“If we don’t go in, we might regret it when we’re old,” she said.

I turned and looked at her. This thought appealed to me in a profound way. Even as a child I thought about the past with an intensity that bordered on brooding, obsessively categorizing memories in order to hold on to them for as long as possible—forever I hoped. And because I was seventeen, I thought a lot about the future, too, what it might hold for me, who I would be then, in the unknown places of my life. But to combine the past and future like that, to imagine the present moment as I might remember it in the future, this layering of time, this positioning and repositioning myself in relation to time: it felt like a gift this girl was giving me, and I looked at her with gratitude.

Her name was Mary. We did go in the river. In some future world, our future selves smiled and were pleased that we did it, even though the shock of the cold water and the difficulty of exiting a swift current onto slippery, weedy banks made it far more dangerous than we’d expected.