What was the secret of Abraham Lincoln's success in dealing with people?
Incredibly, this is not just a question that a business journalist would ask. Dale Carnegie himself--the legendary author of How to Win Friends and Influence People--asked the exact same question on page 8 of that famous book.
Carnegie was in a unique position to know the answer. Four years before How to Win Friends came out, he authored a book called Lincoln the Unknown, which he spent three years working on.