There may be biological reasons compelling people to become couples or overwhelming psychological imperatives, but it is clear to me that if you pin somebody down and say why are you with someone there is no real reason. Why else do people say "it was fate" or "inevitable" or "I felt like I knew 'X' all my life?" It is the mystical center to most relationships that is the enduring charm of falling in love.

But more and more in this technical society it is not a question of romantic "fate" that draws people together as much as proper and correct circumstances. Not "proper and correct" in Victorian terms, where they were moral imperatives, but proper and correct in a programmatic way, the kind of language your bank machine tells you, "incorrect password, please code in your password again."

There are proper places to meet people, e.g. the office, the apartment complex, through a calculated dinner invitation. There are improper places: street corners, for instance, or in line at a bank machine (one comes across as not only being after a person for sex but also for their fortune).

But of all the improper places, the least savory is the subway. No doubt because we all, whether we admit it or not, feel trapped down there. If someone starts a conversation you can't ignore them by looking at the scenery. Besides, you don't get on a subway like you do a train or a plane, for the pleasure of travel. You go underground to go a short distance quickly.

But the circumstance of Metro doesn't mean that one can't experience that mystical sensation. It just might mean that you don't consummate it. I know, it has happened twice to me, and those unconsummated encounters stick in my memory's craw.

I remember in the winter of 1977, when I was living in New York there was a blizzard. The snow filled the air relentlessly for 48 hours, and the only way to get around the city was by subway. It was in the afternoon and I was riding back to the East Village from uptown.

There was a dark-haired woman with a small delicate face standing near me in the graffiti-encrusted car. I could tell she was French. There were so many things I seemed to know about her from what she was wearing, a sheepskin coat probably obtained in North Africa (what sort of person goes to North Africa?) to the way she looked at me (Parisian women do not feel assaulted by a man's glance, they are more than capable of staring down unwelcome lookers).

We exchanged smiles but no words. To my delight she got out at 14th Street, my stop. We staggered wordlessly through the snow drifts down 4th Avenue. I wouldn't start conversation lest she think I was trying to pick her up. Then extraordinarily enough she turned down 12th Street when I did. She stopped to light a smoke in the lee of a building. When it turned out to be a Gauloise, I knew the things that I had filled in about her were right.

I felt as if I knew her so well we could start something very nice. Once before I felt that I knew someone else that well without knowing them and we had been in love for a couple of years. I struck up a conversation in my well accented, badly grammared French and the conversation flowed for the space of 200 yards till we reached the door of my building.

I thought to ask her in for tea or cocoa, and would have, if I met her in a "proper" circumstance. But how can you ask someone you met in the subway up to your apartment without seeming like a lecher? I didn't get her name but for 3 1/2 years I have not forgotten her or that encounter which lasted no more than 10 minutes.

The reason I bring this up is it happened again the other day. I got on a Metro at Capitol South taking my customary end seat so that I could lean against the partition. Sitting opposite me, under the system map was a woman with sandy colored-hair and a sweetly turned up nose. She had a portfolio case such as commercial artists carry and a large leather sack. She was looking nowhere in particular. I knew from her face she was on her way to a job interview. It is a face I have often worn. I got the feeling she wasn't too comfortable in that role, wasn't used to wearing her job-seeker's wool skirt and checked blouse. Her hands were the hands of an artist: square, the fingers full, the nails pared all the way down.

While I was filling in her life story (as if I had known her for a long time), she turned and looked at me. I smiled an embarrassed smile as if I'd been discovered writing an unauthorized biography. She smiled an embarrassed smile at having caught me.

A woman getting off the train interrupted our little moment to compliment her on the leather sack. The subway pressed on, and I remembered the incident 3 1/2 years ago. I said to myself the heck with propriety, I'm going to ask her out to lunch -- if she gets off at McPherson Square as I was.

At Federal Triangle she began to tie up her sack and I knew she was getting off at Metro Center. My heart sank. Lunch in the company cafeteria was off. Dinner at my place was off. A Christmas elopement was off.

She slung the bag over her shoulder and stood up. We were looking at each other again. The same kind smile passed between us. The door opened and our eyes held as she stepped toward it. As she moved past me she said "bye-bye" with only enough breath for me to hear. Her mouth didn't smile but loosened at the corners, about as far as the constraints of propriety allowed. Then she was gone, and in a lonely world two more people had missed each other.

Well, I've learned my lesson. It is not possible to predict when the mystical certainty that I have just met my partner for life will strike. But I assure you that if it comes on as the door is shutting at Metro Center, I will tear through and with words and actions start what fate decrees. So please, don't be startled.