Every week, it seems, social scientists find another way in which we divide ourselves into groups. There’s the Generation Gap, the Gender Gap, the Education Gap, people who shop at the Gap and those who don’t, omnivores and vegans, liberals and conservatives, book readers and Kindle readers, rock climbers and normal people, texters and grown-ups, gay and straight, rich and poor, black and white, boxer/briefs and a million other splits. The one that has been bothering me most recently is the gap between the people who read and respond to their email instantly and those who don’t.

”Did you get that thing I sent you about that TV show?” I asked my friend Barbara as we were waiting in line at the Stop and Go Away gas station.

”Oh, I didn’t read my email yet this week,” Barbara said.

”How can you not read your email for a week?” I said a little louder than I had intended. Other people in the line with smartphones in their hands were staring at her as if she’d said that clubbing baby seals was a good idea. They were probably tweeting our conversation. Or recording it on video, hoping we’d say or do something so incredibly stupid that it would get 12 million hits in the next five minutes and get them a three-picture deal with some Hollywood movie company.