destroy humanity by killing the first man.

Of course, he told himself, that would obliterate, along with the rest
of mankind's history and comedy and tragedy, the first forty-five years
of his own life. But those years didn't matter. By and large, they were
the hard years. They were the years of toil and struggle, to give him
the position and wealth he now had. Position and wealth--which he never
would enjoy. Let them be obliterated then! With the rest of humanity,
not in any sudden catastrophe, but quickly and without pain, at the
instant First Man is killed....

* * * * *

A week later, he got the crash program underway. Since the world's
scientists, like most of the world's intellectuals, were underpaid, it
was comparatively simple hiring them, especially since this was a time
of international calm. At first the physicists were dubious. Yes, the
theoreticians said, time travel was a possibility. No, the engineers
said, it couldn't be executed.

Execute it, he said. Here's money. Here are facilities. Here is
everything you will need. If what you need doesn't exist, make it, buy
it, steal it--but get it. Our time is limited. We have a year. One year
to make it possible for one man to travel back in time.

After three months, they were shaking their heads.

After six months--when the first terrible twinges of pain had
begun--they began to work feverishly.

Jason Wall went regularly to his physician at this time for the drugs
that could ease his terrible suffering. They spoke, the doctor with no
greater objectivity than Jason Wall himself, of his disease. It was
absolutely incurable. Even a crash program to find a cure wouldn't help
Jason Wall. The damage done to his body was irreversible. And, the
doctor mentioned in passing, it was hereditary. That is, the germ of the
disease, or a predilection for it, or both, were carried in the blood of
mankind like a scourge, had been so carried, as far as medical science
knew, from the dawn of history and before.

If the murder he had planned ever bothered Jason Wall, which is
doubtful, it certainly did not bother him now. What was killing
him--hereditary! Why, the First Man he sought might himself be
responsible. Killing him would almost be a pleasure....

After eight months something began to take shape. It was a little box.
"For hamsters," one of the scientists said.

"Fool! I want to go."

They made the box bigger.

Ten months fr