When I first finished the preceding story, or thought I had, I was left dissatisfied. I lay awake till about 2 A.M. trying to figure out what dissatisfied me, and then decided I had not made my point. I got up, quickly wrote down the last three paragraphs of the story as it finally appeared, ending with that horrified question, and then went peacefully to sleep.

 The next day, I rewrote the last page of the manuscript to include the new ending and when I sent it off to the Times, much as I wanted to make the sale, I indicated where I would be intransigent.

 "Please note," I wrote, "that the ending on an unresolved question is not an accident. It is of the essence. Each reader is going to have to consider the meaning of the question and what answer he himself would give."

 The Times asked for some trivial changes and clarifications but did not allow even a whisper of objection to emerge concerning my ending, I am glad to say.

 My own original title had been "Mathematical Games," by the way, and for a while I considered restoring it in the book version. However, THE LIFE AND TIMES OF MULTIVAC has a swing to it. Besides, a large number of people saw it on the single day during which it was available to the reading public. More people came up to me over the next few weeks to tell me they had read that story than had ever been the case for any other story I had ever written. I don't want them to think I changed the title in order to lure them into thinking they hadn't read the story before, so that they might buy this book, so THE LIFE AND TIMES OF MULTIVAC it stays.

 Among those who saw my story in The New York Times Magazine was William Levinson, editor of Physician's World. In the same issue of the magazine section was an article entitled "Triage." Triage is a system of choosing whom to save and whom to allow to die when conditions do not allow of saving all. Triage has been used in medical emergencies when limited facilities have been applied to those with the best chance of making it. Now there is a feeling that triage might be applied on a worldwide scale, that some nations and regions cannot be saved and that no effort should be made to save them.

 It occurred to Levinson that the subject could be treated through the medium of science fiction and since my name was staring at him on the same contents page, he approached me. I was struck with the idea and agreed at once. I started it on January 19, 1975. Levinson liked THE WINNOWING when it was done and it was all set to appear in the June 1975 issue, when the magazine suddenly suspended publication the issue before.

 Sad and embarrassed, Levinson returned the story, but, of course, it wasn't his fault, so I wrote him a reassuring letter. After all, the story had been paid for and it wasn't likely I couldn't place it elsewhere.

 Ben Bova took it at once, in fact, and it appeared in the February 1976 Analog.

The Winnowing

Five years had passed since the steadily thickening wall of secrecy had been clamped down about the work of Dr. Aaron Rodman.

"For your own protection-" they had warned him.

"In the hands of the wrong people-" they had explained.

In the right hands, of course (his own, for instance, Dr. Rodman thought rather despairingly), the discovery was clearly the greatest boon to human health since Pasteur's working out of the germ theory, and the greatest key to the understanding of the mechanism of life, ever.

Yet after his talk at the New York Academy of Medicine soon after his fiftieth birthday, and on the first day of the Twenty-first Century (there had been a certain fitness to that), the silence had been imposed, and he could talk no more, except to certain officials. He certainly could not publish.

The government supported him, however. He had all the money he needed, and the computers were his to do with as he wished. His work advanced rapidly and government men came to him to be instructed, to be made to understand.

"Dr. Rodman," they would ask, "how can a virus be spread from cell to cell within an organism and yet not be infectious from one organism to the next?"

It wearied Rodman to have to say over and over that he did not have all the answers. It wearied him to have to use the term "virus." He said, "It's not a virus because it isn't a nucleic acid molecule. It is something else altogether -a lipoprotein."

It was better when his questioners were not themselves medical men. He could then try to explain in generalities instead of forever bogging down on the fine points. He would say, "Every living cell, and every small structure within the cell, is surrounded by a membrane. The workings of each cell depend on what molecules can pass through the membrane in either direction and at what rates. A slight change in the membrane will alter the nature of the flow enormously, and with that, the nature of the cell chemistry and the nature of its activity.

"All disease may rest on alterations in membrane activity. All mutations may be carried through by way of such alterations. Any technique that controls the membranes controls life. Hormones control the body by their effort on membranes and my lipoprotein is an artificial hormone rather than a virus. The LP incorporates itself into the membrane and in the process induces the manufacture of more molecules like itself-and that's the part I don't understand myself.

"But the fine structures of the membranes are not quite identical everywhere. They are, in fact, different in all living things-not quite the same -in any two organisms. An LP will affect no two individual organisms alike. What will open the cells of one organism to glucose and relieve the effects of diabetes, will close the cells of another organism to lysine and kill it."

That was what seemed to interest them most; that it was a poison.

"A selective poison," Rodman would say. "You couldn't tell, in advance, without the closest computer-aided studies of the membrane biochemistry of a particular individual, what a particular LP would do to him."

With time, the noose grew tighter about himself, inhibiting his freedom, yet leaving him comfortable-in a world in which freedom and comfort alike were vanishing everywhere, and the jaws of hell were opening before a despairing humanity.

It was 2005 and Earth's population was six billion. But for the famines it would have been seven billion. A billion human beings had starved in the past generation, and more would yet starve.

Peter Affare, chairman of the World Food Organization, came frequently to Rodman's laboratories for chess and conversation. It was he, he said, who had first grasped the significance of Rodman's talk at the Academy, and that had helped make him chairman. Rodman thought the significance was easy to grasp, but said nothing about that.

Affare was ten years younger than Rodman, and the red was darkening out of his hair. He smiled frequently although the subject of the conversation rarely gave cause for smiling, since any chairman of an organization dealing with world food was bound to talk about world famine.

Affare said, "If the food supply were evenly distributed among all the world's inhabitants, all would starve to death."

"If it were evenly distributed," said Rodman, "the example of justice in the world might lead at last to a sane world policy. As it is, there is world despair and fury over the selfish fortune of a few, and all behave irrationally in revenge."