Answer:
I tremble at each breath of air, and yet can heaviest burdens bear. What am I?
I am there when you sit, but gone when you stand. What am I?
I can be heard in a court or carried with you.
I can only be played on a windy day
I cannot be other than what I am, until the man who made me dies. Power and glory will fall to me, only when he last closes his eyes.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.