Napoleon Hill, a Great Depression-era author and former advisor to President Franklin D. Roosevelt, decided more than 76 years ago to figure out the key to
To do so, he interviewed more than 500 of the most successful men in the U.S. at the time, such as Henry Ford, Andrew Carnegie, and Charles M. Schwab.
The result of his findings, "Think and Grow Rich," became one of the best-selling books of all time and sealed Hill's reputation as a pioneer of self-help literature.
We've scoured its pages to come up with some of Hill's best insights about wealth,