This led me to think of a point in history where a simple article of faith was suddenly exposed as a lie. My notes say, "Someone has invented a telescope or a microscope which shows the belief is not true; that person is pulled in front of the High Priest to judge his heresy. The High Priest is a sophisticated man and feels the symbolic truth is more important than the literal; but he knows that for some people, this tiny thing will undermine their faith."

It's a stock situation in science fiction: the moment when science confronts religion. But then I decided things would be more interesting if, for some people, the microscope/telescope did confirm their simple faith. Some metaphoric claim of something in a person's blood…and with the poor quality of early microscopes, some people saw what their religion claimed would be there. Over the generations, those who did see something would intermarry with one another, tending to reinforce the trait within that population…

A pattern immediately presented itself: first Leeuwenhoek with the microscope; then Darwin explaining how selection processes emphasized the trait; and finally, a modern scientist who could lay out the whole situation with real chemistry. The parallels with Rh-positive and Rh-negative blood were just begging to be exploited…and the story wrote itself from there.

"Sense of Wonder": A while back, the editors of a proposed new sf magazine called Sense of Wonder sent mail-outs to various science-fiction writers, inviting us to submit stories. The editors wanted "big" stories that worked on a cosmic scale, stories designed to evoke the famous "sense of wonder" that many people believe is the heart of science fiction. The letter specifically mentioned Dyson spheres and other large-scale props of classic science fiction as examples of what the editors were looking for.

I certainly have nothing against Dyson spheres, ringworlds, and the like—I've read plenty of good stories that use such knick-knacks. However, I was feeling in a contrary mood the day I received the mail-out. My first response was "Big stage props aren't what you need for sense of wonder. I'll show you sense of wonder!"