People don't buy what you do; they buy why you do it. And what you do simply proves what you believe

  In the book Simon Sinek speaks of golden circle is based on golden ratio. He lives in New York and teaches a graduate-level class in strategic communications at Columbia University. Books
Sinek Simon (2009).

com. His 2009 book on the same subject Start With Why: How Great Leaders Inspire Everyone to Take Action (2009) delves into what he says is a naturally occurring pattern grounded in the biology of human decision-making that explains why we are inspired by some people leaders messages and organizations over others.