<p>Booms are not all alike. Nor slumps. Shocks and institutions are never exactly the same. Yet the late 1990s boom, the slide into slump and recent rebound has a striking similarity to the boom of the roaring 1920s, the deep decline in the early '30s and initial rebound. I see the two experiences as primarily driven by analogous forces and common mechanisms -- both non-monetary. And I believe that the rest of the present decade will tend, barring new shocks, to resemble the rest of the '30s -- a recovery with investment and employment below historical norms.</p>