When I was very young I would play with my younger sister weighty moral games. I remember one of them which said ... Suppose by pushing down just here (I touched my thumb down on a spot of grass) we could kill one Chinese at the other end of the world and we'd get $1 million. Should we do it?

No, Tish said. That would be murder.

I tried to prolong the grand inquiry by pointing out that there were different kinds of murder, some more sinful than others. "It wouldn't be as though we pulled out a pistol and shot the man."

She lingered for a moment, but came back. No, she said.

Caeteris paribus , we understand President Bush to be talking about the same thing. The circumstances are different, but, he insists, there is someone down there and we can't just do him in, whatever the benefits.

We dig in and learn the first lesson, which is that there is a difference between adult stem cells and embryonic stem cells. In vetoing the one bill, while signing another one more limited in scope, Mr. Bush made the point that he could not in good faith direct public money to embryonic stem cell research. Such research accepts the temptation of using embryonic stem cells to support experimental work, never mind that such work is designed to intervene in the development of cells in such a way as might hinder, or even eliminate, malformations that produce sundry human afflictions.

Much of the public has taken to using Alzheimer's disease as the symbolic corpus vile in the picture. It became universally known that Ronald Reagan had contracted Alzheimer's when he wrote his famous public note announcing his withdrawal from public life. As a matter of rhetorical convenience, advocates of stem cell research started advertising their work as the beginning of a cure for that disease. Early on, the explicit sanction of Mrs. Ronald Reagan was solicited, and she gave it. Understandably -- one dead Chinese vs. one live Ronald Reagan?

President Bush makes several points. The first is that it was he who initiated the very idea of federal subsidies for stem cell research by scientists bent on improving human health. What he did, in 2001, was authorize the use of stem cell lines that had already been extracted from embryos. Continued...