Once the school doors had opened across the street and swallowed up the city’s kids for another year, I sat on my porch and marveled at the sudden silence of a crisp, blue morning that hinted at fall.

The streets that had buzzed with youthful energy only a day earlier now seemed so eerily still and breathless that I could almost hear the sounds of autumn leaves scraping along the lawns and the sidewalks. The vibrant shouts of the children were muted, and the mad fleets of bicycles and skateboards that had whirled through the neighborhood had been temporarily corralled.

The first day of school alters the atmosphere of a community with surprising abruptness, offering the most poignant signal that another delirious summer is fading fast and a quieter, more reflective season lies just ahead.

For the youngest children, this anxious day would represent their first big break from home, the most critical of the many separations from the familiar that they would confront in their lives. In time, the school would become their stage, their unexplored universe, their field of honor, victory and defeat. And each morning the kids would look at the classroom walls to find the rules to live by hanging there like cardboard commandments.

Cover your coughs and sneezes.

Brush your teeth.

Get plenty of rest.

Don’t run.

Don’t shove.

On this calm morning, I was reminded of an old black-and-white photo my mother sent me a while back. It showed a group of schoolchildren in rows, tallest in the rear and shortest in front. The kindergarten boys wore white shirts and neckties, for this was long ago, and the girls all wore skirts. I stood somewhere near the middle, with three teeth missing from my lopsided, self-conscious smile. The rules to live by hung on the wall in the background of the picture, the same clear advisories that now guided children 45 years later.

Stop, look, and listen before you cross the street.

Here we are responsible, here we know the rules, and what to do, what to do.

Be kind to one another.

Don’t fight.

Play fair.

The standards of human conduct would never again be this unmuddied and straightforward.

I went back to my newspaper, and steeped myself in another day’s dismal reality. I read that a Moscow subway bomber had killed 10 innocent people “in support of Muslims of Chechnya,” and that suicide terrorists had blown up two buses in southern Israel, killing 16 and wounding 100. I read that an American soldier would be facing further charges for abusing Iraqi detainees at Baghdad’s Abu Ghraib prison. I read of yet another corporate executive who had siphoned millions from his company to fund his lavish lifestyle, and of the record 23 athletes cited for doping in the recent Olympic Games in Athens.

Soon, the school kids would grow up to discover how easily the basic old rules are violated and manipulated, how complicated and ambiguous the adult code of conduct could be.

Don’t fight, unless …

Play fair, unless …

Be kind to one another, unless …

Here we are responsible, unless …

By far, the toughest lessons the kids will ever be forced to learn.