Rocks and water droplets
There was a huge rock on the top of a high mountain. The rock was always proud of itself and huge. One day, a small drop of water looked at the rock and said.

"I'm not as big and strong as you are, rock, but one day I will pierce you."

Rock laughed at the drop of water.
"A little drop of water like you will pierce me? No chance!"

But the drops didn't give up. They were constantly falling towards the same spot every day. Time went by, and the drops didn't rest as the days went by and the sun changed.

Years later, the rock began to form small holes. And eventually, the water droplets penetrated the rock. The rock only realized then.

"Small but constant effort can eventually beat the strongest in the world."