The Book that will not only leave you 'feeling' good but also 'think' good. In The Master Key System, presented as a series of twenty-four lessons, Charles Haanel discusses everything from how to feel healthy to how to become wealthy. Using precise logic and a consistent, common-sense frame-work, Haanel shows us how to achieve that what we most desire. The Master Key System is rumored to be what inspired Bill Gates to leave Harvard and start Microsoft.