On January 8, 2018, I interviewed John C. (Jack) Bogle, the founder of Vanguard, the largest manager of U.S. index funds and the second largest investment management organization in the world. Bogle, born in 1929, founded Vanguard in 1974 and launched the first index mutual fund, designed to track the S&P 500, in 1975. He served as chairman and CEO …