What is the sound of one hand clapping?

When I first heard this well-known Zen koan, I think I was about 12 years old. I was a literal-minded little smart-aleck, and I'm pretty sure I did what I suspect a lot of kids do: I waved one hand back and forth a few times, said "Duh!" or the equivalent, and concluded that people who fall for this stuff are idiots.

One grows up, however, and over the years this has become one of my favorite existential jokes, along with Woody Allen's one about the guy who thinks he's a chicken (which I take to be about life in general, not just about relationships). 

A couple of days ago, the koan popped into my head again. This time, the insight it propounds really, really really struck me. Sometimes when you realize something, it just sort of sits there like a frog on a lily pad, blinking at you with a bored expression on its face. Other times, the universe briefly falls apart and puts itself back together before your eyes. This was one of the latter realizations. (And it was turtles all the way down.)

Which I think is the point of koans, so I'm glad the universe took the trouble. It and I are so often at two with each other. 

I'm sure my cluttered, concept-riddled mind will continue to run things most of the time, for better or worse, but it's nice to know that once in awhile that other mind can put in an appearance.