Scene I: Yesterday.  Two working-class guys are conversing on the street.  One is a native-English speaker; one is a native-Spanish speaker.  They are speaking to each other in English.  They seem to be discussing a small construction project.  Their talk is cordial; they don't seem to be friends, but they're friendly enough with each other.  Their conversation comes to an amicable enough end; they shake hands, and the native-English speaker turns to walk away down the sidewalk.  The native-Spanish speaker says, "muchos gracias, amigo!"  The native-English speaker says, in an unmistakably hostile tone, "say it in fucking English," and shakes his head in disgust.  He says this so that the native-Spanish speaker can hear him, and he doesn't look back at the native-Spanish speaker to smile and let him know that he's joking, because he's not joking.

Scene II: Today, a half-block away.  I am in a deli buying some chewing gum and a cup of deli coffee.  A man with a Greek accent is railing to the Asian guy behind the counter (I think he was Chinese) about the price of cigarettes, which have gotten very expensive in New York over the past few years.  There is a line of five people or so at the register.  Three of them buy cigarettes, and each time this happens, the Greek guy gets more worked up.  "Ten dollars and thirty-five cents!  You know how much those used to be??  Thirty-five cents!!!  A quarter and a dime into the machine and you got a pack of cigarettes!!!!  In 1980, this was!!!!!"  It's my turn at the register, and I'm paying for my coffee and gum and being particularly glad not to be buying cigarettes, and the Greek guy decides to take off.  In parting, maybe to show the Asian guy that there are no hard feelings about the cigarettes (which are so expensive now purely on account of taxes), he says, "God bless you.  In your language, God bless you."  And he smiles a big, genuine smile, and the Asian guy smiles a big, genuine smile back at him.

And the melting pot boils on.