A professor was taking a boat across a wide river. The boatman, humming a happy tune as he rowed, was clearly no scholar, so the professor decided to test him.
“My man, can you read?” he asked.
“Nope.” The boatman shook his head. “Never had time to learn.”
"Is that so? Then you’ve lost one quarter of your life. Can you write?”
The boatman said, "No, sir. Too busy making a living.”
“Then you’ve lost another quarter of your life. Can you do arithmetic?”
“No. Never saw much use for it on the river.” "Pity, now you've lost another year of your life."
A silence fell between the two men for several moments until the boatman said, "Sir, may I ask you a question?”
“Certainly, my man.”
“Can you swim?” Asked the boatman. The professor smirked, and chuckled. “No friend. In my learned profession, there was never any need for that.”
“Well, thats too bad because this boat’s leaking and we’re going to sink.”