The master key system: how to apply the law of attraction in your life

The Master Key System is a personal development book by Charles F. Haanel that was originally published as a correspondence course in 1912. Though originally a 24 week correspondence course, it was published in book form in 1916. It was first published as a book in 1916 by Psychology Publishing, St. Louis and The Master Key Institute,
New York.

Along with “The Science of Getting Rich”, by Wallace D. Wattles, the Master Key System is the source of Rhonda Byrne’s inspiration for the book and the film “The Secret” (2006).