At 77, John C. Bogle shows no signs of slowing down. The founder of the Vanguard Group -- who prefers to be called "Jack" -- came to our interview today with great energy and enthusiasm... and without the entourage that often accompanies other business leaders we interview. He was very easygoing, smiled often, and was exceptionally polite to our technical crew.

Personally, I like interviewing Bogle because he advocates a sensible approach to investing that is easy to understand. In a nutshell, he recommends investors put nearly all of the US portion of their stock portfolio into a S&P 500 or Wilshire 5000 index fund. That may not be much fun, but he says it will payoff long term because studies show that, over time, index funds beat actively managed funds.

These days, Bogle is highly critical of the mutual fund industry. In fact, he says there’s very little he does like about the mutual fund industry now. He is disgusted by the way most fund families promote performance and charge hefty fees. He is also highly critical of heavy portfolio turnover -- a sign, he says, that managers are trading and not investing.

Bogle clearly sees himself as an advocate for individual investors. After our interview, I pressed him on what his next objective will be. I suggested that he might want to tackle mutual fund marketing, since nearly every fund promotes performance. Bogle agreed it’s a problem, and said that he’d like to see ads that tout low fees, diversification, turnover, and “more sensible” criteria.

I think it was particularly timely to have Jack Bogle on the program today -- a day when the Dow plunged over 200 points. In his view, days like today really shouldn’t matter for long term investors.