Grant Miller asks, "What is the sound of one hand clapping?"
And the Idea of Progress responds.
"What is the sound of one hand clapping?" is what is referred to as a Zen kōan, which is a story or phrase designed to shed wisdom in a way that can't be explained logically. It is perhaps the most famous of all kōans.
But what is the answer? Does it have one?
Yes it does.
The question would typically be asked by a monk of a neophyte. The correct answer is to raise one hand, palm forward.
One hand clapping.
(And believe it or not, I didn't have to look that up)
EDIT: Reading the Wikipedia article on kōans, I was reminded of another famous one (and my favorite). A monk asks a novice, "Does a dog have the Buddha-nature?" and the novice responds, "Woof!" (Technically, he says "Wú!" which means 'none' or 'nothing,' but also sounds like a dog barking)