Music is made of what we do when we move, and we can only move in certain ways, in certain ranges of tempo because of the inherent constraints that our bodies offer, or you can call them 'affordances' - that's another word for me. It's a little more positive; doesn't make it seem like a limitation, but rather, a set of opportunities. You can say that that's part of music making, but there's also the imagination. The power of the imagination is kind of trumping - sorry to have to use that word.