So what do we know about the world's second most powerful man? Under the sage-like grey beard, how much do we understand about the rather tweedy Ben Bernanke, the Federal Reserve chairman who is set to slash interest rates for the world's biggest economy by a third within a week?

Until Mr Bernanke was nominated by President Bush to run America's central bank in 2005, he was best known as one of the world's leading academics on the Great Depression.

Quite handy one might think, as the housing recession and credit crisis threaten to propel the American economy into one of the most difficult periods since the 1930s. As an academic, Mr Bernanke roundly accused the Fed of making things worse during the Depression, a position that some of his Wall Street critics may now find ironic.

Unlike his predecessor, Alan Greenspan, who acted fast, by instinct and demanded unanimity among his rate-setting colleagues, Mr Bernanke is an academic, albeit an ambitious one, to the core. The last academic before Mr Bernanke to run America's central bank was Arthur Burns, Nixon's Fed chairman. Some have remarked that one of the few similarities between Mr Bernanke and Mr Greenspan is that they can both play the saxophone.

The 54-year-old Jewish Republican from Dillion, South Carolina - the son of a local drug store owner - is known for running the Federal Open Market Committee with a collegiate, inclusive style, politely listening to his colleagues, rather like a university staff meeting. His democratic style has, by some, been blamed for the lack of clarity by the Fed concerning the bank's perception of the trajectory of the economy and what they plann to do about it. In his defence, Mr Bernanke is doing a better job at herding Fed members to form some kind of consensus than Mr Greenspan did at the same stage in his tenure. Early on in Mr Greenspan's chairmanship, he suffered three dissents on one interest rate move.

Mr Bernanke had always wanted to be an academic - having secured a place at Harvard as an undergraduate, he then studied at the Massachusetts Institute of Technology (MIT), home of the brightest and best of America. In the small world of econometrics, he was supervised for his doctortal thesis by Stanley Fischer, the Governor of the Bank of Israel, who has been quoted of saying of Mr Bernanke since that "Every central-bank governor goes through tests of some sort. Usually the gods oblige by providing the test early on."

By the age of 31, Mr Bernanke has secured a position within the economics department at Princeton University. His projection into politics came after President Bush asked him to become a Fed Governor in 2002. His greatest ambition is to be a great central banker, not a politican, his former colleagues have noted.

The father-of-two, married to Anna, a Spanish language teacher, is a man who prides himself on planning, and methodical thought. According to Roger Lowenstein, the author of "While America Aged", Mr Bernanke reckoned he could tell a good deal about a person depending on how quickly they took their car keys from their pocket on their way to their vehicle. Not for Mr Bernanke, the impulsive last minute fumble for his keys by his car door - the keys had been located well before arriving in the car park.

For some the anecdote could not be more ironic. Mr Bernanke's thoughtful, dogged approach, has been perceived by some as misguided, blaiming him for helping to cut rates too far, and for too long in 2003, keeping them high for too long, and being too slow (some would say blind) to the risk of the housing recession and the credit crisis, now, cutting rates too late.

As the expert on the Great Depression, Mr Bernanke is known to say that "If you want to learn about seismic activity, you study earthquakes, not tremors."

Mr Bernanke may have his biggest lesson just in front of him.

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