Sir Arthur Conan Doyle, the creator of Sherlock Holmes, was waiting for a taxi outside the railway station in Paris. When the taxi pulled up, he put his suitcase into it, and then got into the taxi himself. As he was about to tell the taxi-driver where he wanted to go, the driver asked him: "Where can I take you, Mr. Doyle?"

Doyle was astounded. He asked the driver if he knew him by sight. The driver said: "No Sir, I have never seen you before." Doyle was puzzled and asked him how he knew that he was Arthur Conan Doyle.

The driver replied: "This morning's paper had a story that you were on vacation in Marseilles. This is the taxi-stand where people who return from Marseilles always wait. Your skin color tells me you have been on vacation. The ink-spot on your right index finger suggests to me that you are a writer. Your clothing is very English, and not French. Adding up all those pieces of information, I deduce that you are Sir Arthur Conan Doyle."

Doyle exclaimed, "This is truly amazing. You are a real-life counter-part to my fictional creation, Sherlock Holmes."

"There is one other thing," the driver said.

"What is that?" Doyle asked. "Your name is on the front of your suitcase."

It wasn't the powers of deduction. It was the power of observation. That taxi driver's lenses were clean and keen enough to observe what was going on around him.