Who is the enemy? In our rather antagonistic society, the finger of blame is pointed alike at big corporations, accused of paying big bonuses to execs while skimping the workers, and at unions, said to extort undue wages and concessions for their members.

Both extremes at one time or another are alleged to have brought the economy to its knees.

And then there is the side issue, always there, always simmering, of immigration and migrant labor, legal and illegal. Some say these workers take jobs from Americans. Others say they do only the work that lazy, entitlement-grabbing Americans won’t touch.

Perhaps there is some truth in each exaggerated portrayal. In all the posturing, we tend to lose sight of one fact: The American economy has been the envy of the world for generations. It is huge. It is usually healthy. When it’s not healthy, and we are just starting to emerge from a dreadful malaise, it has usually managed not to crash entirely. And it employs millions of people...