There is a bank in New York City at 72nd Street and Broadway where you are only allowed to deal with a human teller if you have $5,000 or more in your account. If you have less money than that, you have to conduct routine business with an electronic machine.

Ever since I read about this new Citibank policy, I have been trying to figure out what it means. I don't think this is just another Manhattan eccentricity, or another symbol of the world's most impersonal city.

The way I see it, the Citibank is on to something big. What we have here is the ultimate two-track, two-class system. To the rich go the human beings. The rest of us get the machines.

An angry customer accused the bank of being "elitist." But you see, that's the point. People have become the ultimate luxury. The government considers them an extravagance. Industry calls them an indulgence. And the middle class can't afford them.

A couple of generations ago, wealth was measured in material goods like indoor plumbing, or a matching set of silverware. When I was a kid, it was a television set or a single-family house.

Back then, the rich were different from the rest of us because they had, you know, things. Luxury was the first name of a car. Now if you want to know who's rich, you don't add up their possessions, you calculate their access to what is truly precious: people.

Trend-spotters date the people problem from World War II, when household workers began to disappear and the middle class was tracked onto machines. We learned to bring clothes to one and dust to another and call it convenience.

Today few have real live people who take care of their houses. The rest have machines with user-friendly names that just sound human: names like lawnmower, vacuum cleaner, dishwasher.

The same thing has happened in the marketplace. When our grandparents went grocery shopping, people handed them goods, such as tomatoes. (These were real live tomatoes, too-- but we won't get into that.)

Now we go to supermarkets and only the fanciest little grocery stores that specialize in out-of-season asparagus, stock up on helpers. They are added on to the bill, sort of like truffles. Under the two-track system, the customers who frequent designer salons and elegant restaurants and fancy hotels and make person-to- person calls get to deal with humans, who ask them nearly extinct questions like, "May I help you?"

The rest of us go through life in discount stores and automats and motels, talking to answering services and automated voices and watching our bills calculated by computer. We are virtually untouched by human hands, except for those that self-serve us.

It's not only middle-class Americans who have been priced out of the market. It's also our institutions. A community college in Maryland has invited a computer to deliver the commencement speech. Soon you may have to go to Harvard to hear a person.

Now, at Citibank, even middle-class money is considered too chintzy to be handled by such an expensive commodity. As the bank executives (you only meet them if you have millions in your account) point out, a machine can handle 2,000 transactions a day and work 168 hours a week. A teller can only handle 200 transactions, work 30 hours a week and then has the nerve to take coffee breaks.

I don't know where the two-track trend will lead, but I have a suspicion. Remember the economist who recently announced that the cost of raising a middle-class child was now over $200,000? I wonder if they sell booties to fit machines.

Copyright (c) 1983, The Boston Globe Newspaper Company