Jason Zweig had this to say (excerpts):
Investing has yielded a few stars so famous they are known by first name. Warren Buffett is one. Peter L. Bernstein -- the economist, investment consultant and prolific author who died on June 5 at 90 -- was another.I've read many books and articles over the years written by Mr. Bernstein and always felt fortunate that he shared his thoughts and insights. The willingness to accept uncertainty in the realm of investing (and life in general) is a valuable lesson.
In his almost 70-year career, he taught economics at Williams College, worked as a portfolio manager at Amalgamated Bank and ran the investment-counseling firm of Bernstein-Macaulay, co-founded by his father and Frederick Macaulay, who invented the modern discipline of bond investing.
In 1974, as Wall Street was suffering its worst market decline since 1929, Mr. Bernstein co-founded the Journal of Portfolio Management to improve risk management with insights from academic research.
In 1970, he asked rhetorically, "What are the consequences if I am wrong?" and said "no investment decisions can be rationally arrived at unless they are [based upon] the answer to this question." He counseled investors to take big risks with small amounts of money rather than small risks with big amounts of money.
The same focus on the consequences of error was one of the main themes of "Against the Gods," which he published more than a quarter-century later.
Also in 1970, Mr. Bernstein wrote: "We simply do not know what the future holds." Over the ensuing decades, he returned again and again to that phrase in his speeches, articles and books, because he felt it captured the central truth about investing.
Asked in 2004 to name the most important lesson he had to unlearn, he said: "That I knew what the future held, that you can figure this thing out. I've become increasingly humble about it over time and comfortable with that. You have to understand that being wrong is part of the [investing] process."
( re: uncertainty see also here here here and here)
There were many who did not ask the question: what if I am wrong?
I can not predict, but I can observe. The trick is learning what observations are worth making and then using that information to construct workable contingencies.