Answer:
What hangs others yet can unintentionally hang itself?
What is that which, though black itself, enlightens the world without burning?
Sleeping during the day, I hide away. Watchful through the night, I open at dawn's light. But only for the briefest time, do I shine. And then I hide away. And sleep through the day.
Five hundred begins it, five hundred ends it. Five in the middle is seen. First of all figures, the first of all letters. Take up their stations between. Join all together, and then you will bring before you the name of an eminent king.
Reaching stiffly for the sky, I bare my fingers when its cold. In warmth I wear an emerald glove and in between I dress in gold.
You use it between your head and your toes, the more it works the thinner it grows.