While street performance/movement-based arts like juggling have sort of been collected together under the term 'flow arts', "flow" itself is a much broader term. It's very difficult to describe in words but its sort of the convergence point where diligent practice and a meditative state of mind come together to produce much greater than average results.
I've heard writer friends talk about it when, after months of hard work on a story, they experience a writing session where the tale seems to be practically writing itself. Some of them have used the word "creepy".
I believe the term was first used in professional sports for when a highly trained athlete experienced the "zone" during which something practically superhuman suddenly seems very easy, almost like a larger force was acting through them. For some people its almost religious, but I view it from a purely secular perspective.
It's addictive too - when you experience the state, you tend so spend a good deal of time subconsciously seeking it out again. I think for some artists, much of the motivation comes from a desire to seek out the high of a flow state.
Usually it lasts until precisely the moment you become consciously aware of it, then it vanishes and you screw up again. Anyone who's tried golf may understand it in these terms: if you think too hard as you're swinging, you'll almost always screw up the shot. All the sweet shots come from a curious, peaceful, non-thinking sort of place. Pro golfers are adept at achieving the state.
Anyways, I'm almost 100% certain that the same effect is felt in the practice of music too, in fact I wouldn't be surprised if music was the original "flow art". If any of you have had similar experiences with your instruments I'd love to hear about it.
