An amusing story, the truth of which I am uncertain.

Roger Bacon was said to have built a mechanical head that worked from a clockwork like mechanism that could think and act, but not speak. Weary of hacking for the night, he decided to go to sleep, but he told his apprentice to immediately wake him up if the head did anything. A little later, the head spoke, and it said, "Time is." The apprentice was too afraid to wake Bacon up, however, and so he didn't do anything about it. A bit after that, the head spoke again, saying, "Time was." Again, the apprentice was much too afraid to awake his master. The head then spoke a third time, this time saying, "Time past." The head then proceeded to blow up. Finally, the apprentice was freaked out enough to wake Bacon up. Unfortunately, Bacon could not repair the head, and it never worked in any capacity again.

What do you suppose Bacon did to his apprentice?

And the moral of the story is: sleep is the adversary, and you should never trust anything important to your apprentice (I know I never do).