Southern Europe has not done enough to enhance its competitiveness, while northern Europe has not done enough to boost demand. Debt burdens remain crushing, and Europe's economy remains unable to grow.

The 24% unemployment reached at the depths of the Great Depression was no picnic.

As for the single market, the E.U.'s landmark achievement, there is no question that a euro zone breakup would severely disrupt its operation in the short run.

Southern Europe has not done enough to enhance its competitiveness, while northern Europe has not done enough to boost demand. Debt burdens remain crushing, and Europe's economy remains unable to grow.

More than the Big Mac, Coca Cola, or Levi's 501 jeans, the dollar is surely the United States' signature export.

The 1992 crisis proved that the existing system was unstable. Not moving forward to the euro would have set up Europe for even more disruptive crises.

The consequences of a collapse would not be pretty. Whichever country precipitated it - Germany by threatening to abandon the euro, or Greece or Spain by actually doing so - would trigger economic chaos and incur its neighbours' wrath.