Greenspan is the Federal Reserve Chairman. The Federal Reserve, or the Fed, was established in 1913 as an independent agency of the government and given the monumentally important task of controlling the banking system and the money supply. In other words, the Fed controls the lifeblood of the American economy: money and credit.
Since the Fed can increase or decrease the size of the money supply at will, he can theoretically control inflation, bank lending, employment patterns, physical investment decisions, etc. Unfortunately, the economy is far too complex for any one person to understand completely. Thus, the Fed is required to be one of the nation's most intelligent economists, able to make huge decisions on the fly, forced to watch hundreds of economic indicators, and knowledgeable in the subtlest points of microeconomic and macroeconomic theory. As evidence of these needs, one need only look at the huge calamities created by lesser Feds in the past.
Check out the biography. Look at his homepage. Or just read a comic.
