Answer:
Dies half its life. Lives the rest. Dances without music. Breathes without breath.
There is one word that stands the test of time and holds fast to the center of everything. Though everyone will try at least once in their life to move around this word, but in fact, unknowingly, they use it every moment of the day. Young or old, awake or in sleep, human or animal, this word stands fast. It belongs to everyone, to all living things, but no one can master it. The word is?
Many have heard it, but nobody has ever seen it. It will not speak until spoken to. What is it?
This thing all things devours: Birds, beasts, trees, flowers; Gnaws iron, bites steel; Grinds hard stones to meal; Slays king, ruins town, And beats high mountains down.
What goes around and around the wood, but never goes into the wood?
You use it between your head and your toes, the more it works the thinner it grows.