Answer:
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.
Runs smoother than any rhyme, loves to fall but cannot climb.
What is put on a table, cut, but never eaten?
I am the third from a sparkle bright, I thrive throughout the day and night. Deep in the path of a cows white drink. I've had thousands of millions of years to think. But one of my creatures is killing me. And so the question I ask to thee, is
You can hold it without using your hands or your arms. What is it?
You use it between your head and your toes, the more it works the thinner it grows.