The concept of a MasterMind was first introduced by Napoleon Hill. Napoleon Hill (1883-1970), author of "Think and Grow Rich" was an American author, best known for the 25 year commission he received from Andrew Carnegie (1835 – 1919) who commissioned Napoleon Hill to interview over 500 millionaires.
During these interviews, he acquired informationand publish his findings about the similarities in traits, habits and a formula by which these people acquire wealth and success. The book "Think and Grow Rich" remains a popular reference today.
Napoleon Hill wrote about the mastermind group principle as:
The coordination of knowledge and effort of two or more people, who work toward a definite purpose, in the spirit of harmony."
He continues…
No two minds ever come together without thereby creating a third, invisible intangible force, which may be likened to a third mind [the master mind]."