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 boon One empty, and one full.
What get wet while drying
What has four wings but cannot fly and uses the wind but does not know why?
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
You heard me before, yet you hear me again, then I die. Until you call me again.
People take me on walks and I run and have fun. What am I?