Answer:
I am black when I am clean and white when I am dirty?
There is a creature of God whose body is hard; it does not wish to eat unless you strike its head.
It holds most knowledge that has ever been said. But is not the brain, is not the head. To feathers and their masters, it's both bane and boon One empty, and one full.
We travel much, yet prisoners are, and close confined to boot. Yet with any horse, we will keep the pace, and will always go on foot.
When I'm born I fly. When I'm alive I lay. When I'm dead I run.
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?