During the upheavals of 2007-09, the chairman of the Federal Reserve had the name of a Victorian icon on the tip of his tongue: Walter Bagehot. Banker, man of letters, inventor of the Treasury bill, and author of Lombard Street, the still-canonical guide to stopping a run on the banks, Bagehot prescribed the doctrines that--decades later--inspired the radical responses to the world's worst financial crises. Born in the small market town of...