The Master Key System by Charles F. Haanel (Unabridged Original Edition, in twenty-four parts with questionnaire and glossary) is a 1912–1916 New Thought self-help course later collected as a book. It is one of the main sources later popularized by The Secret. Haanel, a St. Louis businessman, first sold it as a 24-week correspondence course. The edition in your photos keeps the original structure: 24 lessons, a psychological self-chart at the front, end-of-lesson questions, a glossary, and extra Q&A. The book itself warns readers not to race through it like a novel. Take one part per week, do the exercise, then move on. What the book claims The core idea is simple and repeated: thought is causative. The universe, in this system, is mental. Your predominant thoughts, especially those held with feeling and concentration, attract matching conditions. Harmony between the conscious mind (the director) and the subconscious (the power that actually builds results) is the “master key.” Negative, fearful, or scattered thinking produces matching results; clear, constructive, persistent thinking does the opposite. Related claims: - Visualization plus emotion plus action turns mental pictures into results. - Concentration is a trainable skill, not a gift. - The individual is not separate from a larger intelligence (“In Him we live and move and have our being” is used as a focus phrase). - Health, money, and circumstances are treated as effects of mental cause, not as random luck. Influences include New Thought, bits of the Bible, Theosophy, and older esoteric language. It is not a scientific treatise; it is a practical metaphysics manual from the early 20th century. How it is built Each of the 24 parts typically has: - An introduction - Numbered teaching paragraphs - A short daily exercise (sit still, quiet the body, then focus) - Questions and answers Early exercises are basic: sit motionless, inhibit random thought, release physical tension. Later ones add visualization of a desired outcome, concentration on a single idea, and identification with a larger spiritual source. The book assumes you will practice 4–7 days on each lesson before advancing.