Time and again, the Federal Reserve's expansions have come under fire, but Emre Kuvvet's recent discovery ("Sun Shines on Fed 'Doomsday Book,'" op-ed, Dec. 12) offers a fresh insight into how those expansions got off the ground. As Prof. Kuvvet notes, the Doomsday Book he unearthed "reveals a fascinating history of diverging perspectives on the Federal Reserve's emergency powers." Yet it is revealing not only for the Federal Reserve's past actions.