|Two mice met in the early nineteen-sixties, when manned flights in orbit were as yet in the planning stage. After the usual exchange of pleasantries, one said, "But you look worn out, Michael. What's the matter?"
Michael shrugged his little shoulders and said, "Life isn't easy for us scientists, you know. I'm in space research, and those experimental flights in rockets, with the weightlessness and the acceleration and the uncertainty of safe return -- Well, it's hard on one's nerves."
"In that case," said his friend, "why don't you quit and take a job in some other line of work?"
"That's easy to say," said Michael, "but stop and think - Is a job in cancer research any better?"