The whole scene takes no more than 30 seconds.
A six-pack of teen-age boys in sneakers and shorts, with baseball caps turned front and back, hanging out on a steamy summer night.
Two girls - 14 or 15, no older - in halters and shorts, walk down the street, their sandals slapping the concrete.
The boys check them out, who's hot, who's not. They close ranks, narrow the sidewalk, so the girls must pass single file.
It's then that I see the girls' antennae go up, notice the way they speed-read the scene, the boys, and the single file between play and danger. The taller girl strikes a pose as a good sport but not a willing player. The smaller takes on a role neither offended nor interested.
The boys stare; the girls smile slightly but make no eye contact. The oldest and boldest of the pack pretends to untie one girl's halter top as she goes by. The girlfriends reach the corner and break into nervous giggles.
Thirty seconds and the boys, like sidewalk hall monitors, have let them pass. It's over.
For once, I don't take this scene for granted. I'm struck tonight by how carefully, precisely, the girls read these boys. How they calibrate both the danger and their own reaction.
How much time and energy went into acquiring these street smarts. Where did they learn? Did their parents teach them to be sexually literate? For their own safety.
Safe sex - no, safe sexuality - is on my mind. In the weeks since I wrote about the Central Park assaults on some 50 women in broad daylight, my mail has been filled with people, many sharing my dismay. But in the mix, there were questions: Didn't I see how some women were playing along? Didn't I see what some women were wearing?
One man described women on the infamous videotapes who would ``giggle and laugh as the guys doused them with water. Only when they felt things were getting `out of hand' did they complain. ... They got exactly what was coming to them.''
Another man wrote about female ``exhibitionists'' who send the ``wrong message'' to men: ``It's akin to dangling a pork chop over a pack of starving wolves.''
A woman wrote of ``skin'' fashions, of women with expressions that said ``Hi Sailor, want to have some fun? All sailors want to have fun.''
And still another reader forwarded a newspaper column on the Central Park assaults by Stanley Crouch that detoured onto ``scantily clad young women'' and told approvingly of a father admonishing his teen-age daughter, ``You are not leaving this house looking like a prostitute.''
I won't revisit the argument that safety can be found in a dress code. If that were true, rape would have been much rarer among our crinoline-covered foremothers. Such a belief leads backward to the sad, distorted thought of a Bangladeshi woman. Brutally disfigured by acid, she proclaimed herself a convert to purdah: ``If I had been kept under the veil, Rakim (her assailant) would not have seen me or been able to talk to me.''
But I am struck by the difficulty our daughters still have being safe and sexual. They are supposed to calibrate the continuum from horseplay to harassment to assault. The culture expects them to be sexy but not ``pork chops,'' to attract men and beware of them. And to maneuver carefully through this terrain, single file.
Remember the sexual assaults at Atlanta's Freaknik celebration, the rapes at Woodstock? Some women were labeled ``fair game.'' In Central Park, ``good sports'' who laughed as their T-shirts were sprayed with water were less credible ``victims'' when those T-shirts were torn off.
Boys - and men - are also subject to double messages. They're surrounded by R-rated images of playgirls who just wanna have fun, and lectured on sexual harassment. They know girls who want to be seen but not stared at.
But girls are the more endangered of our species. So even those who want our daughters to be comfortable in their own skins, to feel powerful in their own bodies, and to be sexually at ease, end up teaching them to be wary.
Girls learn to read boys. They learn that they have to maneuver - single file - to be safe. They learn who owns the street and the park. These lessons of sexual danger sometimes linger even in relationships with men they love.
There are times when I'm convinced we've updated the book on men and women. But until we teach our sons their own set of reading lessons, this piece of the story will remain the same.
Ellen Goodman is a columnist for the Boston Globe.