IT'S A METAPHOR, if you stop to think about it: the train slides smoothly through the black tunnel from station to station, stopping at each in perfect obedience to the computer. But it refuses to open its doors. No one can get on or off. What does the driver have in mind? Gradually word spreads among the passengers that there is no driver. He stepped out of the cab some time ago and is down that tunnel, far behind.

What would you do in a case like that? Bang on the Glass? Scream? It wouldn't be very helpful. Take bets from your fellow passengers regarding what will happen when the train hits the end of the track?

(Metro deplores the use of the verb "hits", its trains are well-behaved, it says, and the computer would have neatly parked this one, driverless, on an empty track at the Dupont Circle station. The computer is benevolent, according to Metro; you are wrong in thinking that it is out to get you.)

when all of that actually happened, on an otherwise uneventful Monday morning, one passenger -- Kilena Loveless, a Greenbelt accountant -- rose to the occasion. She did what all of us hope that we would have done -- although some of us suspect, in our hearts, that we would have thought of it only afterward. Riding in the first car, she tried the door to the driver's compartment and, finding it locked, she jimmied it with a hair clasp. She first punched the button that stopped the train at the next station, then the button that opened the doors.

It was a fine demonstration of initiative, citizen participation and the ability -- increasingly important in our society -- to find the right button. It was an example of what most americans like to think is the American way. Metro's computer, on the other hand, is an example of the way we all seem to be going.