In the early 1900s, Andrew Carnegie was building his fortune in the steel industry.

One day a young man came into his office selling consultant services.

He told Carnegie that in only 15 minutes, he could provide information — free of charge — that would multiply Carnegie’s resources.

There was only one stipulation: if Carnegie used the advice and found it successful, he had to promise the consultant an appropriate payment.

Once they agreed, the man shared a productivity secret that transformed Carnegie's business.

What did the consultant tell him?