​In a terror attack’s wake, a great American city does what it knows too well: How to face down a nightmare 

For a generation now, New Orleanians have been tested by a bevy of high-profile scourges. And so many have internalized, perhaps too well, a hard and potent lesson that often gets celebrated here as “resilience” but really boils down to this: How to carry on in the face of the unimaginable.