Answer:
Never resting, never still. Moving silently from hill to hill. It does not walk, run or trot. All is cool where it is not. What is it?
Never ahead, ever behind, yet flying swiftly past, for a child, I last forever, for adults, I'm gone too fast.
An open ended barrel I am shaped like a hive. I am filled with the flesh and the flesh is alive.
I can run but not walk. Wherever I go thought follows close behind.
I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?
Runs over fields and woods all day. Under the bed at night sits not alone, With long tongue hanging out, Resting at your feet until we go for a walk