Answer:
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 boonย One empty, and one full.
I weaken all men for hours each day. I show you strange visions while you are away. I take you by night, by day take you back. None suffer to have me, but do from my lack.
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.
It's got twists and turns, but has no curves. Twist it to fix it, turn it to ruin it. What is it?
Scythe of darkness, Shadowโs light. Guiding eye of thirteenth sight.
A doctor might remove one from the neck of a Dracula victim.