The Master Key System book by Charles F. Haanel

The Master Key is here given to the world as a means of tapping the great Cosmic Intelligence and attracting from it that which corresponds to the ambitions, and aspirations of each reader. The Master Key teaching has been published in the form of a Correspondence Course of 24 lessons, delivered to students one per week for 24 weeks. The reader, who now receives the whole 24 parts at one times, is warned not to attempt to read the book like a novel, but to treat it as a course of study and conscientiously to imbibe the meaning of each part - reading and re-reading one part only per week before proceeding to the next. Otherwise the later parts will tend to be misunderstood and the reader's time and money will be wasted. Used as thus instructed "The Master Key" will make of the reader a greater, better personality, and equipped with a new power to achieve any worthy personal purpose and a new ability to enjoy life's beauty and wonder.