A student watched as his master sat on the ground and rubbed a large stone with a smaller one.
Curious, he finally asked, “Master why are you rubbing that large stone so vigorously with the smaller one?”
The master looked up and said, “I am polishing the large stone with the smaller one too make a mirror.”
“But master,” the student replied, “no amount of rubbing those stones together will make a mirror.”
The master smiled and said, “Quite right! … Just as no amount of thinking will ever make you see your true nature.”