Answer:
Sharp and long, flag of the world. What is it?
I am whole but incomplete. I have no eyes, yet I see. You can see, and see right through me. My largest part is one fourth of what I once was.
I have a neck but no head. I have a body but no arm. I have a bottom but no leg.
I appear in the morning. But am always there. You can never see me. Though I am everywhere. By night I am gone, though I sometimes never was. Nothing can defeat me. But I am easily gone.
When the horse strokes the cat, the wood begins to sing.
I can only be played on a windy day