The Master Key System - Charles F. Haanel - "Knowledge doesn't apply itself" - Charles F. Haanel. Charles F. Haanel was an American author, millionaire, entrepreneur, and businessman who shared his path to mastery through this book. The Master Key will not only help solve your problems, but also to become aware of opportunities, and make use of them. It's the key to universal forces, helping you to change the circumstances on the outside through altering your predominant mental attitude. Thought being energy, and concentrated thought being concentrated energy, concentration is the key to impact on the subconscious mind, thus aligning the Finite (conscious) with the Infinite (subconscious).