“We’re brothers, so I guess she would be the same as mine, but Mr Million says she went away a long time ago.”

“Not the same as yours,” my aunt said. “No. I could show you a picture of your own. Would you like to see it?” She rang a bell, and a maid came curtsying from some room beyond the one in which we sat; my aunt whispered to her and she went out again. When my aunt turned back to me she asked, “And what do you do all day, Number Five, besides run up to the roof when you shouldn’t? Are you taught?”

I told her about my experiments (I was stimulating unfertilized frogs’ eggs to a sexual development and then doubling the chromosomes by a chemical treatment so that a further asexual generation could be produced) and the dissections Mr Million was by then encouraging me to do, and while I talked, happened to drop some remark about how interesting it would be to perform a biopsy on one of the aborigines of Sainte Anne if any were still in existence, since the first explorers’ descriptions differed so widely and some pioneers there had claimed the abos could change their shapes.

“Ah,” my aunt said, “you know about them. Let me test you, Number Five. What is Veil’s Hypothesis?”

We had learned that several years before, so I said, “Veil’s Hypothesis supposes the abos to have possessed the ability to mimic mankind perfectly. Veil thought that when the ships came from Earth the abos killed everyone and took their places and the ships, so they’re not dead at all, we are.”

“You mean the Earth people are,” my aunt said. “The human beings.”

“Ma’am?”

“If Veil was correct, then you and I are abos from Sainte Anne, at least in origin; which I suppose is what you meant. Do you think he was right?”

“I don’t think it makes any difference. He said the imitation would have to be perfect, and if it is, they’re the same as we were anyway.” I thought I was being clever, but my aunt smiled, rocking more vigorously. It was very warm in the close, bright little room.