Gregory Arnfeld was not actually dying, but certainly there was a sharp limit to how long he might live. He had inoperable cancer and he had refused, strenuously, all suggestions of chemical treatment or of radiation therapy.

He smiled at his wife as he lay propped up against the pillows and said, “I’m the perfect case. Tertia and Mike will handle it.”

Tertia did not smile. She looked dreadfully concerned. “There are so many things that can be done, Gregory. Surely Mike is a last resort. You may not need it.”

“No, no. By the time they’re done drenching me with chemicals and dowsing me with radiation, I would be so far gone that it wouldn’t be a reasonable test…And please don’t call Mike ‘it.’“

“This is the twenty-second century, Greg. There are so many ways of handling cancer.”

“Yes, but Mike is one of them, and I think the best. This is the twenty-second century, and we know what robots can do. Certainly, I know. I had more to do with Mike than anyone else. You know that.”

“But you can’t want to use him just out of pride of design. Besides, how certain are you of miniaturization? That’s an even newer technique than robotics.”

Arnfeld nodded. “Granted, Tertia. But the miniaturization boys seem confident. They can reduce or restore Planck’s constant in what they say is a reasonably foolproof manner, and the controls that make that possible are built into Mike. He can make himself smaller or larger at win without affecting his surroundings.”

“Reasonably foolproof,” said Tertia with soft bitterness.

“That’s an anyone can ask for, surely. Think of it, Tertia. I am privileged to be part of the experiment. I’ll go down in history as the principal designer of Mike, but that will be secondary. My greatest feat will be that of having been successfully treated by a minirobot-by my own choice, by my own initiative.”

“You know it’s dangerous.”

“There’s danger to everything. Chemicals and radiation have their side effects. They can slow without stopping. They can allow me to live a wearying sort of half-life. And doing nothing win certainly kin me. If Mike does his job properly, I shall be completely healthy, and if it recurs” -Arnfeld smiled joyously-”Mike can recur as well.”

He put out his hand to grasp hers. “Tertia, we’ve known this was coming, you and I. Let’s make something out of this-a glorious experiment. Even if it fails-and it won’t fail-it will be a glorious experiment.”

Louis Secundo, of the miniaturization group, said, “No, Mrs. Arnfeld. We can’t guarantee success. Miniaturization is intimately involved with quantum mechanics, and there is a strong element of the unpredictable there. As MIK-27 reduces his size, there is always the chance that a sudden unplanned reexpansion will take place, naturally killing the-the patient. The greater the reduction in size, the tinier the robot becomes, the greater the chance of reexpansion. And once he starts expanding again, the chance of a sudden accelerated burst is even higher. The reexpansion is the really dangerous part.”

Tertia shook her head. “Do you think it will happen?”

“The chances are it won’t, Mrs. Arnfeld. But the chance is never zero. You must understand that.“

“Does Dr. Arnfeld understand that?”

“Certainly. We have discussed this in detail. He feels that the circumstances warrant the risk. “ He hesitated. “So do we. I know that you’ll see we’re not all running the risk, but a few of us will be, and we nevertheless feel the experiment to be worthwhile. More important, Dr. Arnfeld does.”

“What if Mike makes a mistake or reduces himself too far because of a glitch in the mechanism? Then reexpansion would be certain, wouldn’t it?”

“It never becomes quite certain. It remains statistical. The chances improve if he gets too small. But then the smaller he gets, the less massive he is, and at some critical point, mass will become so insignificant that the least effort on his part will send him flying off at nearly the speed of light.”

“Well, won’t that kill the doctor?”

“No. By that time, Mike would be so small he would slip between the atoms of the doctor’s body without affecting them.”

“But how likely would it be that he would reexpand when he’s that small?”

“When MIK-27 approaches neutrino size, so to speak, his half-life would be in the neighborhood of seconds. That is, the chances are fifty-fifty that he would reexpand within seconds, but by the time he reexpanded, he would be a hundred thousand miles away in outer space and the explosion that resulted would merely produce a small burst of gamma rays for the astronomers to puzzle over. Still, none of that will happen. MIK-27 will have his instructions and he will reduce himself to no smaller than he will need to be to carry out his mission.”

Mrs. Arnfeld knew she would have to face the press one way or another. She had adamantly refused to appear on holovision, and the right-to-privacy provision of the World Charter protected her. On the other hand, she could not refuse to answer questions on a voice-over basis. The right-to-know provision would not allow a blanket blackout.

She sat stiffly, while the young woman facing her said, “ Aside from all that, Mrs. Arnfeld, isn’t it a rather weird coincidence that your husband, chief designer of Mike the Microbot, should also be its first patient?”

“Not at all, Miss Roth,” said Mrs. Arnfeld wearily. “The doctor’s condition is the result of a predisposition. There have been others in his family who have had it. He told me of it when we married, so I was in no way deceived in the matter, and it was for that reason. that we have had no children. It is also for that reason that my husband chose his lifework and labored so assiduously to produce a robot capable of miniaturization. He always felt he would be its patient eventually, you see.”

Mrs. Arnfeld insisted on interviewing Mike and, under the circumstances, that could not be denied. Ben Johannes, who had worked with her husband for five years and whom she know well enough to be on first-name terms with, brought her into the robot’s quarters.

Mrs. Arnfeld had seen Mike soon after his construction, when he was being put through his primary tests, and he remembered her. He said, in his curiously neutral voice, too smoothly average to be quite human, “I am pleased to see you, Mrs. Arnfeld.”

He was not a well-shaped robot. He looked pinheaded and very bottom heavy. He was almost conical, point upward. Mrs. Arnfeld knew that was because his miniaturization mechanism was bulky and abdominal and because his brain had to be abdominal as well in order to increase the speed of response. It was an unnecessary anthropomorphism to insist on a brain behind a tall cranium, her husband had explained. Yet it made Mike seem ridiculous, almost moronic. There were psychological advantages to anthropomorphism, Mrs. Arnfeld thought, uneasily.

“Are you sure you understand your task, Mike?” said Mrs. Arnfeld.

“Completely, Mrs. Arnfeld,” said Mike. “I will see to it that every vestige of cancer is removed.”

Johannes said, “I’m not sure if Gregory explained it, but Mike can easily recognize a cancer cell when he is at the proper size. The difference is unmistakable, and he can quickly destroy the nucleus of any cell that is not normal.”

“I am laser equipped, Mrs. Arnfeld,” said Mike, with an odd air of unexpressed pride.