Answer:
This is in a realm of true and in a realm false, but you experience me as you turn and toss.
What has a neck and no head, two arms but no hands?
What can be swallowed, but can swallow you?
What is neither inside the house nor outside the house but a necessity for any home?
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.
What sphinxes employ and players enjoy.