He was called the "closely guarded secret of Silicon Valley." Bill Campbell, the celebrity coach whose advice has helped Google, Apple, Amazon and Twitter make more than a trillion dollars. He taught Eric Schmidt, Steve Jobs, Sergey Brin, Larry Page, Sundar Pichai, US Vice President Al Gore and dozens of other famous people. All his life, Bill Campbell adhered to the principles that invariably led the teams he patronized to prosperity. These principles were assembled and carefully codified by grateful protégés of a distinguished coach.