The Power of concentration
I remember when I was a little boy, my father took me to a cave that extended underground for about a mile. My father held a great torch, and I followed him carefully, while looking at the big shadows on the walls and listening to the echoes of our words.
At least we stopped by some rocks. My father showed me a tongue-shaped rock, about two feet thick projecting from a shelf in the cave. He also showed me a finger-like rock above, from which drops rhythmically dripping down. After I saw both these rocks he said, "I have a question for you. You saw that drop from the ceiling, but did you see where it went?" He looked at me, and held the torch up to help me see better. I noticeed the drops were falling on the rock and passing through it. It was curious because the rock was very thick. I crawled under the rock to see what was going on. I saw that the rock was drilled through one inch in diameter and the drops were passing directly through a tube-like hole and falling on the ground.
"Do you know how it happened?"
"No."
"Think!"
"The drops kept hitting the rock for centuries and they drilled through the rock."
"Yes! I brought you to see this fact and to learn a lesson. A concentrated thought in any direction, if continued, can do things that seem impossible."
When we were just out of the cave, my father looked again into my eyes and said, "The power of thought and the secret of how to think - these are the keys to all locks. Do not forget. The weakest thing is a drop, but it can drill through rock."
Then he jumped on his horse and pulled me up in front of him. We were going through high mountains toward the symphony of sunset. -H. Saraydarian, The Science of Meditation.