“Are you sure four inches is safe?” I called.

“Up to you!” He looked like a friar, with his black ski jacket cinched at the waist and the hood up. “I’m going out on it.”

I plunged through the snow after him, testing the ice first with my foot like the woman in the crosswalk. Solid enough, although the hollow grinding sound my boots made was unmistakable: we were walking over water.

“Your dad plays it safe,” said Robin. “Especially when there’s a guest he feels responsible for.”

“Don’t you feel responsible for people?”

“I’m not worried about four inches. I’ve been on four inches many a time.”

Behind us the side bedrooms were in darkness and so was the attic room, hidden up in the branches, but the front window was ablaze with light, and the four terrace lamps shone in their cages.

“How long do you think those lamps will last?”

“They’re supposed to be outdoor-proof,” said Robin.

“Didn’t you put them in that first year you came up? They’ve held out for two winters.”

“We’ll have to wait and see.”

I turned my back on the lit-up house. Around the shore, the other cottages were mostly in darkness. Norma’s gave off a reassuring glow. I felt a pang to think of her asleep over there with her all-night porch lamp on. “Their house is even more visible in winter.”

“Yes,” said Robin.

“It doesn’t really matter, does it?”

“No,” said Robin.

“Or the color. I kind of like it now. Sometimes I get all worked up about nothing.”

He was backlit, his whole face in shadow.

“The ice is thinner than it used to be,” I said. “We had seven or eight inches when I was growing up.”

“Even thicker up north. We used to drive onto the ice and fish from the seat of a pickup. I wouldn’t do it now.”

“Have you seen that program about walrus mothers fighting for space for their pups? They’re crammed together on these little chunks of ice. They push each other off.”

“No, but I’ve seen icebergs calving. It’s happening so fast.”

The snow stretched out before us in long smooth scallops, ridged like bone.

“If you’d never seen water in solid form, would you guess it would be like that?”

“No,” said Robin. “Ice kind of makes sense. But snow is more like sand.”

“Look at the colors!” Not only the blues, but the violets, grays, purples, and pinks read as variations of white against the dark fringe of the shore. “Doesn’t it seem impossible that all this could go?”

“Once it goes, it goes.”

I kicked at the snow. “Don’t think about it.”

I could not see Robin’s face, but I could feel his eyes on me. Some things were too big to talk about. Eventually he said: “Shall we sneak Alison out here? Not tell your father?”