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.
Regarding the Master Key System, it is important to understand that it is in the application alone that the value consists, which means it is of little value to just read and watch the videos. You must perform the exercises to obtain the benefits. A practical understanding of the Law of Attraction will substitute abundance for poverty, wisdom for ignorance, harmony for discord and freedom for tyranny, and certainly there can be no greater blessing than these from a material and social standpoint.
Visit NewThoughtWisdom.com for more information, videos and ebooks by Charles F. Haanel and other early New Thought authors.
You can read the text version of The Master Key System if you prefer: The Master Key (pdf file)