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 boonΒ One empty, and one full.
The more you take, the more you leave behind.
What has two spines and a lot of ribs, and carries much but never moves?
It is greater than God and more evil than the devil. The poor have it, the rich need it, and if you eat it you'll die.
Vikings use this for warmth.
I am rarely touched but often held. If you are smart you'll use me well. What am I?