A man is driving down the road and 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 very
strange 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." 

The man is disappointed but thanks them anyway and goes about his merry way.
Some years later, The same man breaks down in front of the same monastery.
The monks again accept him, feed him, and again fix his car. That night, he
hears the same strange noise that he had heard years earlier. The next
morning, he asks what it is, but the monks reply, "We can't tell you. You're
not a monk."  The man says, "All right, all right. I'm dying to know. If the
only way I can find out what that sound was is to become a monk, how do I
become 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 sand pebbles, when you find these
numbers, you will become a monk." 

The man sets about his task. Some 54 years later, he returns and knocks on
the door of the monastery.  He says, "I have traveled the earth and have
found what you have asked for. There are 145,236,284,232 blades of grass and
231,281,219,999,129,382 sand pebbles on the earth." 

The monks reply, "Congratulations. You are now a monk. We shall now show you
the way to the sound."  The monks lead the man to a wooden door where the
head monk says, "The sound is right behind that door." The man reaches for
the knob, but the door is locked. 

He says, "Real funny. May I have the key?" The monks give him the key, and
he opens the door. Behind the wooden door is another door made of stone. 

The man demands the key to the stone door. The monks give him the key, and
he opens it, only to find a door made of ruby. He demands another key from
the monks, who provide it. 

Behind that door is another door, this one made of sapphire, And so it went
until the man had gone through doors of emerald, silver, topaz, and
amethyst. 

Finally, the monks say, "This is the last key to the last door." 

The man is relieved to know that he has finally reached to the end . 

He unlocks the door, turns the knob, and behind that door he is amazed to
find the source of that strange sound. 

But he can't tell you what it is because you're not a monk.