A man is driving down the road and his car breaks down near a  monastery.
He goes to the monastery, knocks on the door, and says, "My car  broke down.  Do you think I could stay the  night?"
The monks graciously accept him, feed him dinner, even fix his  car.
As the man tries to fall asleep, he hears a strange sound. A sound  unlike anything he's ever heard before. The Sirens that nearly seduced Odysseus  into crashing his ship comes to his mind. He doesn't sleep that night. He tosses  and turns trying to figure out what could possibly be making such a seductive  sound.
 
The next morning, he asks the monks what the sound was, but they  say, "We can't tell you. You're not a  monk."
Distraught, the man is forced to leave.
Years later, after  never being able to forget that sound, the man goes back to the monastery and  pleads for the answer again.
The monks reply, "We can't tell you. You're not  a monk."
The man says, "If the only way I can find out what is making  that beautiful sound is to become a monk, then please, make me a  monk."
The monks reply, "You must travel the earth and tell us how many  blades of grass there are and the exact number of grains of sand.
When you  find these answers, you will have become a monk."
The man sets about his  task. 
  
 After years of searching he returns as a gray-haired old man and knocks on  the door of the monastery.
A monk answers. He is taken before a gathering of  all the monks.
"In my quest to find what makes that beautiful sound, I  traveled the earth and have found what you asked for: By design, the world is in  a state of perpetual change. Only God knows what you ask. All a man can know is  himself, and only then if he is honest and reflective and willing to strip away  self deception."
The monks reply, "Congratulations.   You have become a monk. We shall now show you  the way to the mystery of the sacred sound."
 
The monks lead the man to a wooden door, where the head monk says,  "The sound is beyond that door."
 The monks give him the key, and he opens the door. Behind the wooden door is another door made of  stone. The man is given the key to the stone door and he opens it, only to find  a door made of ruby. And so it went that he needed keys to doors of  emerald, pearl and diamond.
Finally, they come to a door made of solid  gold. The sound has become very clear and definite. The monks say, "This is the  last key to the last door."
The man is apprehensive to no end. His life's  wish is behind that door!
With trembling hands, he unlocks the door, turns  the knob, and slowly pushes the door open.
Falling to his knees, he is  utterly amazed to discover the source of that haunting and seductive  sound......
But, of course, I can't tell  you what it is because you're not a monk.