A mastermind is a small group of trusted advisors who meet regularly with the goal of improving each other’s lives or careers. The collective brainpower of the group — otherwise known as a “mastermind” — is turned towards a single problem. A mastermind can solve problems and take advantage of opportunities in a way that an individual person can’t. They are based on the simple premise that a whole can be greater than the sum of its parts. John Lennon plus Paul McCartney is not additive, it’s exponential. They have been around in various forms, under various names, for hundreds of years.