Is koan Buddha-nature?
Sit. Walk. Think. Just be.
Zen is the Japanese version of Ch'an, the Chinese combination of Taoism and Buddhism. Most of its terminology is borrowed from Buddhism, but it has a very Taoist approach to language and approaches the world in a similar child-like way. Lineage is considered very important, and teachers' job is to set up the environment where a student may realize What It's All About (attain enlightenment). While meditation plays a large role in Zen practice, it is most famous for its koans, questions which challenge the way we think about the world.
There's a Zen Meditation group on campus. I can't find the link right now, but if you're interested, I can probably point you in the right direction. I've sat with them a few times. It was an interesting experience. I became very aware of several parts of my body, especially my legs which were starting to fall asleep. After sitting for 20 minutes or so we'd get up and walk around the room in a circle a few times and then sit again. Unfortunately, I've typically had more pressing things to do with an hour.
But Zen philosophy is much more interesting to me than Zen practice anyway. Koans are exactly the sorts of questions I like to ask -- they're sort of the metaphysical equivalent of puns. I had a small book in my backpack for quite a while that I'd read when I'd be on the bus for five minutes or something. It was full of Zen sayings from traditional Japanese koans ("A student asked the master, 'Does a dog have Buddha-nature?' The master replied, 'Mu.'") to witticisms from Yogi Berra ("Nobody goes there anymore. It's too crowded."). I wish I knew where that book was.
The idea of "mu" (which is often translated "no") is that it "unasks" the question. For example, if I ask "Is justice red or blue?" the correct answer is neither "red" nor "blue," but "That's a bad question; there isn't a meaningful answer." Buddhist teachings say that Buddha-nature is in everything, so the "answer" to the mu koan is as follows. Everything is Buddha-nature; by asking if a dog has Buddha-nature, you imply that there is a distinction between things which have Buddha-nature and things which don't.
One of my favorite characterizations (stereotypes, perhaps) of Zen is its focus on nothing (which is not the same as not focusing on anything). For instance, when I walked during commencement in May '02, I received a diploma case, but I won't get an actual diploma until this semester. So I set up the case and said "It's my Zen diploma." This sort of statement is not intended solely as a joke.