ZIPLOCK SECURITY.(The Talk of the Town)

It is a matter of public record that bags--schoolkids' backpacks, mainly, but also women's handbags--are getting bigger all the time. An undocumented corollary is that bags are more plentiful, too--that there are more bags per capita on the street today than at any other time in history. If this is true (and if you go out right now and start counting you will be convinced within minutes that it is), possible explanations could include the proliferation of portable gadgets, a reading-material boom, a trend toward tight or pocketless clothing, or cheap bagmaking labor overseas.

But, much as nature finds ways (disease, famine) to combat overpopulation, city life has thrown up impediments to bags. To enter many public buildings, theatres, ballparks, and--theoretically, at least--subway stations, you must submit to a search or even go bagless. The city is a thicket of bag policies. It is hard to keep them all straight, and you're never sure, when leaving home for the day, whether it might be a bad idea to bring one along. One rule, at least, is easy to remember: you may not put a bag on a seat in a subway train. It will cost you fifty dollars.

Last week, the main branch of the New York Public Library got in the game. Students, researchers, writers, historians, idlers, hoboes, and anyone else who has grown accustomed over the years to treating the vast Rose Main Reading Room, on the third floor, as an office or a, well, reading room came up against a new decree. You are no longer allowed to bring a bag larger than eleven inches by fourteen inches into the library. If you walk in with one, you must leave it at the coat check. You may keep its contents with you, however, and the library provides big clear plastic ziplock bags for them. You return them when you retrieve your own bag (and after their visible contents have perhaps invited a "What's your major?" gambit or two). To enforce the eleven-by-fourteen standard, the coat-check attendant at the library has affixed two strips of masking tape to a corner of the counter, a crude version of those boxes you see in airports that help determine whether your carry-on will fit under the seat directly in front of you.

What the library is trying to prevent, in this case, is people taking things out, rather than bringing things in. "It's about collection security," Stewart Bodner, a research librarian, said on ...