John “Jack” Bogle, who died at his home in Bryn Mawr, Pennsylvania, on Wednesday, also left the Securities and Exchange Commission with advice to mull as it marches ahead with its advice-standards package and the much-debated Regulation Best Interest.

A clue to why Bogle has become such leading light is found in his most-recent book, “Stay the Course — The Story of Vanguard and the Index Revolution.”