If Memory Swerves

September 15 will mark five years since the beginning of the economic slump that defines the world we live in. Disaster was in the air already by that day in 2008: real-estate values had been falling for some time, Bear Stearns and several big commercial banks had failed, and the government had taken over the mortgage insurers Fannie Mae and Freddie Mac the previous week. But that Monday morning in September was when the larger economy went over a cliff — after Lehman Brothers, the nation’s fourth largest investment bank, finally succumbed to the effects of the noxious securities on…