“The Others didn’t evolve from them,” I said. You didn’t have to be a xenobiologist to see that.

“Not in any biological sense. About thirty thousand years ago there was a profound disagreement, what you might call a philosophical schism. It was about the fundamental nature of life, and the necessity for, or desirability of . . . its ending. Whether thinking creatures should die.”

“They had a way around it?” Namir said. “Not just longevity, but immortality?”

Spy nodded, but said, “No. Not exactly.

“It’s difficult to put this into terms that have universal meaning. That would mean the same thing, for instance, to humans and Martians.”

“But we can agree about what life is,” I said, “and that death is the cessation of life.”

“I don’t think so,” Snowbird said. “That has always been a problem.”

“Don’t get all spiritual,” Elza said. “As a doctor, I can assure you that dead people are much less responsive than living ones. They also start to smell.”

Snowbird held her head with both large hands, a laughter expression. “But the individual was alive in the genetic material of its ancestors, and also will be alive in the ones that follow after the organism dies.”

“Not me. I don’t have any children and don’t expect any.”

“But it’s not limited to that,” Snowbird said. “Before the individual was born, it was alive in the teachings that would eventually form it. Everyone you meet changes you, at least a little, and so becomes a kind of parent. As you yourself become a parent to anybody’s life you touch. It’s the only way, for instance, that humans and Martians can be related. Many of us feel closely related to some of you. Fly-in-Amber and I are closer to you humans here than we are to many Martians.” And I had been closer to Red, I realized, than I’d ever been to my own father.

“I’ll grant that’s true in a certain sense,” Elza said, “but it’s not as physically real as a genetic connection.”

“You claim your brain is not physically changed by accepting new information? I think that it is.”

“This is good,” Spy said. “It’s one aspect of the disagreement between the Others and you people. But only one aspect.

“Over the centuries, the ones who would become the Others physically isolated themselves, first on an island, then in an orbiting settlement, which grew by accretion. The separation became more complete as the ones on the planet encouraged belief systems that were inward-looking, antagonistic to space travel.

“The Others also pursued research into longevity, which most of the ones on the planet came to consider blasphemous.”

“Let me guess,” Namir said. “There was a war.”

“Several, in fact. Or you could see it as one ongoing war with phases that were decades apart. Centuries.