A pretentious scholar was keen to show off. One day, while being rowed across a stream, he asked the boatman, "Do you understand philosophy?"
"No, sir," replied the boatman.
"Then," said the scholar, "one-fourth of your life is gone."
After a while, he asked again, "Do you know geology?"
"Nothing at all," said the boatman.
"Well, that makes one half of your life gone," declared the scholar.
Just then, the boat suddenly tipped over. The boatman asked, "Can you swim?"
The scholar gasped for breath, "No."
"Then your whole life is gone," said the boatman.