 Why does Simon not bring back a time traveler?
"Providence," Simon told her whilst fiddling with the aspirin bottle, "will provide." Simon said, enigmatically, "Now it comes." The client fussed himself with Betty's assistance into the seat, bug-eyed Simon, said finally, "You know my name, that's pretty good. When Simon continued to say nothing she ventured, "Time travel is impossible." "Time travelers," she said, not very intelligently. "Then you'll realize that there are a dozen explanations of the paradoxes of time travel. It's my contention that within a century or so man will have solved the problems of immortality and eternal youth, and it's also my suspicion that he will eventually be able to travel in time. "The usual explanation, Betty, is that they can't afford to allow the space-time continuum track to be altered. If, say, a time traveler returned to a period of twenty-five years ago and shot Hitler, then all subsequent history would be changed. In that case, the time traveler himself might never be born. Simon said, "You want to hire me to find a time traveler and in some manner or other—any manner will do—exhort from him the secret of eternal life and youth, which you figure the future will have discovered. If you could go back a few thousand years, the things you would wish to see would be a Roman Triumph, perhaps the Rites of Dionysus, or one of Alexander's orgies.
 The authorities would not allow him to do anything that might significantly change the space-time continuum
 He knows that Arth is Mr. Oyster setting a trap to ensnare Simon, who is a time traveler himself  Simon is a time traveler himself, and would never reveal the secrets of his fellow time travelers  He became too intoxicated with Arth and sabotaged his own investigation  The authorities would not allow him to do anything that might significantly change the space-time continuum