Mailing List Joke: Art vs. Science

I received this in my gmail from this mailing list I'm a part of in terms of teachers and talking about educational issues and such. I thought it was pretty clever.

Art vs Science

A scientist and a poet were traveling in the same compartment on a train. They had never met before, so naturally there wasn't much conversation between the two.
The poet was minding his own business, looking out the window at the beauty of the passing terrain. The scientist was very uptight, trying to think of things he didn't know so he could try to figure them out. Finally, the scientist was so bored that he said to the poet, "Hey, do you want to play a game?" The poet, being content with what he was doing, ignored him and continued looking out the window, humming quietly to himself. This infuriated the scientist, who irritably asked again, "Hey, you, do you want to play a game? I'll ask you a question, and if you get it wrong, you give me $5. Then, YOU ask ME a question, and if I can't answer it, I'll give YOU $5."

The poet thought about this for a moment, but he decided against it, seeing that the scientist was obviously a very bright man. He politely turned down the scientist's offer.
The scientist, who by this time was going mad, tried a final time. "Look, I'll ask you a question, and if you can't answer it, you give me $5. Then you ask ME a question, and if I can't answer it, I'll give you $50!"

Now, the poet was not that smart academically, but he wasn't totally stupid. He readily accepted the offer. "Okay," the scientist said, "what is the EXACT distance between the Earth and the Moon?" The poet, obviously not knowing the answer, didn't stop to think about the scientist's question.
He took a $5 bill out of his pocket and handed it to the scientist. The scientist happily accepted the bill and promptly said, "Okay, now it's your turn." The poet thought about this for a few minutes and then asked, "All right, what goes up a mountain on three legs, but comes down on four?"

The bright glow quickly vanished from the scientist's face.
He thought about this for a long time, taking out his notepad and making numerous calculations. He finally gave up on his notepad and took out his laptop, using his Multimedia Encyclopedia. After about an hour of this, the poet quietly watching the mountains of Colorado go by the whole time, the scientist FINALLY gave up. He reluctantly handed the poet a $50 bill. The poet accepted it graciously, turning back to the window.

"Wait!" the scientist shouted. "You can't do this to me!
What's the answer?" The poet looked at the scientist and calmly put a $5 bill into his hand.