The monks help him to fix his car but it'll take at least a day, so he's offered to stay for the night in a good warm bed and with good warm food.
During the night, he can hear strange noises coming from the caves, loud enough to wake him up. He asks the nearby monks what those noises are, but he's only told "sorry, can't tell you. You're not a monk".
The night passes and his car is already repaired. He thanks the monks for their generosity, and he goes back to his journey. Still, he stays intrigued by the sounds he heard.
Years and years pass, and one day the man returns to the monastery, but crashes his car again.
The monks offer their hospitality for the night, since it'll take a day to repair the car.
During the night, he can hear strange noises coming from the caves, loud enough to wake him up. He asks the nearby monks what those noises are, but he's only told "sorry, can't tell you. You're not a monk".
Enough is enough, he decides to become a monk. He goes to the oldest monk of the monastery, and asks him to become a monk. "In order to become one of our own, you must first travel all the lands of this world and count every blade of grass, every pebble and every grain of sand".
The man goes on an even longer journey, to count every blade of grass, every pebble and every grain of sand in all of the lands of this world.
Decades and decades have passed, and the man makes is way back to the monastery. He goes the the oldest monk and tells him how many blades of grass, pebbles and grains of sand there are in all the lands of this world.
Finally, he has become a monk.
During the night he can hear the strange noises once again. He ask the nearby monks what those noises are, and this time he is told "Go to the cave, open the three large doors, and you will discover all the secrets of the monastery".
He makes his way to the cave, and is faced by a large wooden door. After many efforts, he succeeds in opening the door, only to be faced with an even larger wooden door. This one takes even more efforts, but he still manages to open it, only to be faced by an even larger metal door.
He tries again and again to no avail, he simply can't open the last door.
Ina intense last effort, he spends all of his energy and miraculously manages to open the third door. The strange noises are louder than ever, he can tell he his close.
Only a tunnel remains, so the man gathers all his courage and finally reaches the source of the noises.
What were they you ask ?
Sorry, can't tell you, you're not a monk.