A minute's worth of knowledge

On one of the flakier programs on CBC Radio One, Freestyle, listeners were challenged to "Impart as much useful knowledge as you can to a resident of the 14th century, in one minute."

I learned about this on an e-mail list used by SCA members, who had some fun with it. One person said: "Don't pet the rat." (My thought was, "don't pet the flea.")

The uselessness of saying either gives one pause. What might be useful? Buy up autograph copies of Petrarch and hold on to them for several centuries?

But someone did come up with this: "Wash your hands after bodily functions and before eating."

Which leaves about 50 seconds to explain the benefits.