Answer:
I am nothing but holes tied to holes, yet am strong as iron.
My second is performed by my first, and it is thought a thief by the marks of my whole might be caught.
If you have it, you want to share it. If you share it, you don't have it.
What flies forever, Rests never?
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.
I always have to work with something in my eye. What am I?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?