Answer:
I am gentle enough to soothe your skin light enough to fly in the sky and strong enough to crack rocks.
Born of sorrow, grow with age, you need a lot of me to be a sage. What am I?
What has a head but never weeps a bed but never sleeps can run but never walks and banks but no money?
What comes once in a minute twice in a moment but never in a thousand years?
I am put on the table, cut, but never eaten. What am I?
No matter how little or how much you use me, you change me every month.