Answer:
Brown I am and much admired; many horses have I tried; tire a horse and worry a man; tell me this riddle if you can.
What surrounds the world, yet dwells within a thimble?
A building where people and stories are on stage
What always runs but never walks, often murmurs, never talks, has a bed but never sleeps, has a mouth but never eats?
What has a head, a tail, is brown, and has no legs?
I always have to work with something in my eye. What am I?