What did Aristotle Onassis mean when he said...

There's a popular quote floating around on the web (on thousands of web pages) - by Aristotle Onassis. According to this quote, he said

"The secret of business is to know something that nobody else knows."
- Aristotle Onassis

What do you think he meant?

Did he mean know something about markets?
About products?
To have knowledge to blackmail others with? (Okay, just kidding about the last one....) :)

I'd love to hear your opinions. This is something I've been pondering since last night....

- Dien Rice