Answer:
I bind it and it walks. I loose it and it stops.
Goes over all the hills and hollows. Bites hard, but never swallows.
A serpent swam in a silver urn, A golden bird did in its mouth abide, The serpent drank the water, this in turn, Killed the serpent. Then the gold bird died.
I can run but not walk. Wherever I go, thought follows close behind.
What measures out time. Until in time all is smashed to it?
Almost everyone needs it, asks for it, gives it. But almost nobody takes it.
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?