An Engineer, Physicist, and Mathematician are each given 100 feet of fence and asked to enclose the largest area possible with it.
The engineer quickly says, “I’ve got it!” and builds a 25 by 25 foot square.
The physicist looks it over, then says, “that’s pretty good, but I think I can do a little better.” He then arranges the fence in a circle with a circumference of 100 feet.
The mathematician then looks at the square, looks at the circle, and after a moment of thought takes a small section of fence, wraps it around himself, and declares, “I define myself to be the outside!”