Answer:
You heard me before, yet you hear me again, then I die. Until you call me again.
What has four legs during the day; and six or eight during the night?
What do you fill with empty hands?
They're up near the sky, on something very tall. Sometimes they die, only then do they fall.
Dies half its life. Lives the rest. Dances without music. Breathes without breath.
I am the fountain from which no one can drink. For many I am considered a necessary link. Like gold to all I am sought for, but my continued death brings wealth for all to want more.