1.   Already, the previous irrational exuberance has already led rather swiftly to irrational pessimism.

2.   History offers more than a few examples of irrational exuberance followed by irrational pessimism.

3.   Just as irrational exuberance can look like wisdom during a sustained stock boom, irrational pessimism can look like wisdom during a sustained stock slump.

4.   So valuations that look very high by historical standards might represent not the rise of irrational exuberance but the decline of irrational pessimism.