IF WE NEEDED ANY REMINDING that our world can change with nerve-rattling speed, we got it last week when the security services uncovered a plot by Islamofascists to slaughter innocent air travelers. Suddenly, a cup of coffee looks suspiciously like a terror weapon, an iPod like an explosives device, and a plane trip becomes even more of a hassle than it has been.

Other changes, less potentially lethal than the latest scare, are in store. The most obvious one underlies the decision of the Federal Reserve Board’s monetary policy gurus to pause in their two-year program of ratcheting up interest rates.