It was on my second day at work that I took my first taxi in Washington D.C. For all practical purposes, the trip was nothing out of the ordinary--just a quick jaunt over to the Martin Luther King public library to renew a dog-eared book on U.S. presidents.

By metro, the actual trip would have been so short--just two stops and $1.10 away--that I had assumed that's how I would get there.

But when I mentioned this assumption to my boss--that I would walk the block to Union Station and jump on the metro--she returned a look of comical disbelief.

"Out of the question," she told me in a laugh. Besides, she said, the metro doesn't give receipts. Pressing two worn five dollar bills into my hand, she told me to go catch a cab.

"Oh, and don't forget to get a receipt," she added with nonchalance as she returned to her desk.

Walking to the elevator, those two bills nestled safely in my pocket, I realized--come to think of it--I had never really "caught" a taxi on my own.

In suburban central Connecticut, where I'm from, taxicabs are reserved for special occasions like the seasonal grandmotherly trips to the airport to catch the 6 a.m. flight to West Palm. Even in Cambridge, the few cabs I've taken have been those at the head of a long line of other taxis, all waiting patiently for their next fares. Once, my friends and I were forced to telephone for a cab when the T had stopped running for the night.

But otherwise, I was a relative novice at this utterly simple thing of taking a taxi. As the elevator ground to a halt at the lobby, I pondered this revelation with curiosity and nervousness.

Taxis, to me at least, had always seemed to be the epitome of being grown-up. They were things of business people in New York City, of opera-goers and those who couldn't be bothered with the subway. For a college student, they represented the ultimate in frivolous but wonderful luxury, up there with flying first class or getting an hour-long massage--well, almost. Still, what typical undergraduate really has ten bucks to squander on a cab when the exact same trip by metro is one-fifth the cost?