Staghorn was constantly having trouble explaining to people that Humanac was not a time machine that could look into the past or future. Its pictures of past events were based upon information already present in its memory cells. Its pictures of future events were predictions calculated according to the laws of probability. But because Humanac, unlike a human, never forgot any of the million and one variables impinging upon any human situation, its predictions were startlingly accurate.
Humanac had never been exposed to pictures of Dr. Peccary's home town nor to those of a girl named Jenny Cheever. It arrived at the likeness of both town and girl through a purely mathematical process.
Staghorn's ultimate purpose in building the machine was to use it in developing a true science of history. Because Humanac was only a machine, Staghorn could alter its memory at will. By removing the tiny unit upon which the Battle of Hastings was recorded and then "re-playing" English history without it, he could find out what actual effect that particular battle had.
He was surprised to discover that it had very little. According to Humanac, the Normans would have conquered England anyway a few months later.
At another time, while reviewing the events leading up to the American Revolution, Humanac had produced a picture of Benjamin Franklin kissing a beautiful young woman in the office of his printing shop. On impulse Staghorn removed this seemingly insignificant event from Humanac's memory and then turned the time dial forward to the present to see what effect, if any, the episode had had upon history.
To his amazement, with that single kiss missing, Humanac produced a picture of the American continent composed of six different nations speaking French, German, Chinese, Hindu, Arabic and Muskogean—the last being the language of an Indian nation occupying the Mississippi Valley and extending northward to Lake Winnepeg. It served as a buffer state between the Hindus and Chinese in the west and the French, Germans and Arabs to the east.
It was Humanac's ability to predict the future consequences of any hypothetical event, however, that made it an instrument capable of revolutionizing history. Once its dependability was thoroughly established, it would be possible for a Secretary of State to submit to Humanac the contents of a note intended for a foreign country, then turn the time controls ahead and get Humanac's prediction of the note's consequences.
If the consequences were good, the note would then be sent.
If they were bad, the Secretary could destroy the note and try others—until he composed one that produced the desired result.