Answer:
One by one we fall from heaven down into the depths of past, And our world is ever upturned so that yet some time we’ll last.
What has four legs during the day; and six or eight during the night?
Halo of water, tongue of wood. Skin of stone, long I've stood. My fingers short reach to the sky. Inside my heart men live and die.
Its title means book.
My teeth are sharp, my back is straight, to cut things up it is my fate.
In your fire you hear me scream! Creaking and whining yet I am dead before you lay me in your hearth.