The Master Key System is a system that teaches the ultimate principles, causes and effects, as well as the spiritual laws that underlie all attainment and success. When you want to attain something, The Master Key System will show you how to get it. The results you will attain from using this system are so startling as to appear incredible. For this reason, more and more people are becoming students of The Master Key System than ever before, even almost a hundred years after it was first published. The Master Key sets out the fundamental principles of life and conscious, rightful living. Basic to his teaching is the correct development and use of mental power — the key to truly creative power and action, harmony and health, love and happiness, and abundant possibilities. Charles Haanel‘s numbered common-sense messages still have a freshness almost one hundred years after they were first assembled. It was Napoleon Hill, author of "Think and Grow Rich", who thanked Charles Haanel in a personal letter for publishing the Master Key System, as Hill deemed it invaluable in achieving his own personal success. That alone speaks volumes.