The Master Key System is a system that teaches the ultimate principles, causes, effects, and 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

In 24 parts, The Master Key sets out the fundamental principles of life and creative living, as Haanel came to understand and apply them. 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. Each part is meant to be studied like a correspondence course lesson, but this is also a book that can be opened at random for whatever gem of advice your eyes happen to fall upon.

This age-old wisdom was written by someone who could perceive and tap into Universal Mind but who seems to have no particular allegiance to any specific system of knowledge. Haanel's numbered common-sense messages still have a freshness 89 years after they were first assembled.

Mr. Haanel died in 1949 and is buried in Bellafontaine Cemetery, St. Louis. Walter B. Stevens described Mr. Haanel as "a man of mature judgement, capable of taking a calm survey of life and correctly valuing its opportunities, its possibilities, its demands and obligations."