"Good lord! You mean that one of the Historical Corps teams screwed up that badly?" We were watching a documentary on the extremely unauthorized transportation of Conrad Schwartz. This had been pieced together, in part from his diary (which he wrote in English to keep it private) and from the readouts of a large number of insect-sized probes initially developed for police work.
When a crime has been reported, our police transport a cluster of probes to the time and scene of the crime. These record everything, which doesn't do the victims much good. Time is a single linear continuum, and you can't "make it didn't happen." If a dead body was found, a human being was dead, and there was nothing that could change that fact. But our methods did assure that criminals committed only one crime and were always caught. As a result, we had an extremely low crime rate and no professional criminals at all.
The probes were eagerly put to use by the Historical Corps, whose occupation was the writing of a truly definitive history of the human race. It was one of their teams that had screwed up.
"Not one team but two. There were ridiculous breaches of security at both the twentieth-century and thirteenth-century portals," Tom said. Tom had been a drinking buddy of mine in the U.S. Air Force long before we got involved with time travel. Much later, we were both surprised to discover that he was my father. There were also certain . . . problems concerning my mother, which I prefer not to discuss. Time travel is not entirely beneficial.
"Well, can't we send him back?" I asked. Anachronisms can be extremely disruptive, and we have no intention of adding to the sum of human misery.
"Impossible. He wasn't discovered, subjectively, until almost ten years later, when I was observing the Mongol invasion of Poland."
"Oh." If Conrad Schwartz had been observed in 1241, then that was an established fact, like the dead body I mentioned earlier. "So there's nothing we can do for the poor bastard."
"We can't bring him back until he has spent at least ten years there, but there are some things that could be done, and in fact, I have already done them.
"Decontamination, for example. The diseases of the thirteenth century are not the same as those of the twentieth century. Thirteenth-century Poland had neither syphilis nor gonorrhea nor acne, and I was not about to see them introduced by our drunken Conrad Schwartz.
"Then again, in the twentieth century smallpox has been eradicated, leprosy is very mild compared to the earlier strains, and the Black Death has become one of the varieties of the common cold.
"The 'fluorescent lights' he slept under in the Red Gate Inn did a lot more than light his way out of the transport capsule. They wiped out every foreign microorganism in him and gave him a complete immunization treatment as well."
One of the nice things about time travel is that it gives you the time to do things that are worth doing. I'd spent much of my life helping to build a technical civilization in the sixty-third millennium b.c. That civilization provides us with most of our personnel and some very high technology. It's also a fine place to live.
"Speaking of diseases, Tom, what was wrong with the priest?"
"Father Ignacy? Nothing. A fine man."
"But those huge, calloused feet!"
"That wasn't a disease. That's what normal human feet look like when they've spent a lifetime walking barefoot over broken rock and snow."
A smiling, nude serving wench announced lunch, and we took a break.
By one, we were back at the screen.