A Physicist and a mathematician setting in a faculty lounge. Suddenly, the
coffee machine catches on fire. The physicist grabs a bucket and
leap towards the sink, filled the bucket with water
and puts out the fire. Second day, the same two sit in the same lounge. Again,
the coffee machine catches on fire. This time, the mathematician stands up,
got a bucket, hand the bucket to the physicist, thus reduce the problem to
a previousely solved one.