Don't peek."

Parents with children prone to snooping for presents aren't the only ones urging that. It's also the recommendation of Jack Bogle, founder of the Vanguard Group, who has just published his 10th book, The Clash of the Cultures: Investment vs. Speculation, in which he offers 10 simple investment tips, including "Remember reversion to the mean" and "Buy right and hold tight."

Most important, Bogle told me last week, investors should resist impulsiveness. "One of the worst mistakes investors make is paying too much attention to the daily ups and downs on Wall Street," Bogle said.

"All too often, we get caught up in the cacophony of the market and make impulsive, emotional, and simply bad investment decisions - we feel the urge to buy after the market has risen up to the heavens, and to sell after it comes tumbling back to Earth.

"My simple advice is this: Turn off the TV, and don't pay much attention to the regular quarterly statements for your retirement plan. Maybe glance at them once a year, or every five years. And if you toss them all away until you retire, when you open that final statement after all those long years of saving and investing, you'll exclaim: 'Where did all that money come from?' You will be completely astonished by the size of your nest egg.

"More importantly, you will have saved yourself from all those potentially disastrous investment decisions along the way. Think about 'Don't Peek' as an important rule of long-term investing."

That's not the sort of advice you'd hear from a Gordon Gekko, the character from the movie Wall Street who said, "Greed is good." Bogle is more apt to say, "Stay the course." He didn't earn his reputation by beating the market. He developed an investment model that sought to keep pace with the market. (Critics actually said that was un-American!) And while his life's work has been about money, the man is not driven by wealth accumulation. At the height of his earnings, this proud Princetonian delighted in giving away half of his income to educational and charitable institutions.

So after 61 years in business, nine books, at least six heart attacks, and a heart transplant, what was left for him to say?

"There's a message there that I don't think anybody else or hardly anybody else is talking about," he told me. "Everybody knows our financial system is a mess, but nobody looks through to see what the data actually show. There is an overwhelming presence of speculation in the market that is crowding out long-term investment. The damage it's doing to our society is great."

Bogle's book offers many suggestions for changing our culture, one of which is to require shareholder approval for corporate political contributions. He also singles out a number of "gatekeepers" who have failed to protect investors, including Congress, the judiciary, the Securities and Exchange Commission, the Federal Reserve, rating agencies, accountants, the financial press, security analysts, directors, and stock owners.

Bogle saves his harshest condemnation for money managers, whose timidity he attributes to a fixation with salesmanship rather than stewardship and long-term governance. Bogle sees a corrosive conflict of interest in which the managers overseeing corporate pension funds, thrift plans, and 401(k)s also own stock in these entities. So "you don't want to offend the management," Bogle says, because "you might lose the account."

"There are only two kinds of clients we institutional managers don't want to offend: actual clients and potential clients," he explained. "And that's a lot of clients."

There is something very humble about Bogle. Time magazine may have said he was one of the 100 most powerful and influential in the world, but he never loses sight of the fact that he had a D-plus in economics and was close to dropping out of Princeton in 1948.

He pulled himself out of that early collegiate hole, but there was, he admits, a bit of luck involved in the path he followed from there - the senior thesis he wrote "quite by accident" after reading about the emerging mutual fund industry.

"I never heard of it. I never had any money to invest," he says. "What we were doing was getting dunning notices from lending companies in my family. So I wrote my thesis about this little industry, tiny industry, tiny, but contentious as the magazine described it. And I got a job here in Philadelphia with Mr. Walter Morgan and the Wellington Fund. With a lot of bumps along the way, the rest is history."

Yes, the history of a rare breed in today's financial sector: a humble millionaire selling simple steps in a time dominated by complex counsel.