I T WAS TIME, I THOUGHT, TO

introduce my 4-year-old son to the joys of the public library. The Arlington branch of my childhood was a favorite place, ruled over by a tall, chinless woman whose sternness added importance to my numerous trips to borrow books. I always checked out the limit, staggering gluttonously home with stacks of books that too often I read instead of doing homework. I had long since decided that should I ever be conscripted to fight for my country on foreign shores, public libraries were high on the list of things I'd be fighting for.

As we started up the steps of the branch in our Capitol Hill neighborhood, I noticed a man stretched out on the retaining wall, reeking and snoring loudly. Oh well, I thought, that's life in the city. It was not the first time my son had seen a bum in a stupor.

We went in and looked around to get our bearings. I heard an odd sound punctuating the cool silence and turned to see a man in periodicals, reading a newspaper and making a compulsive snort every few seconds, the type of noise that comes only from a person whose psyche is somewhat disordered, a sound guaranteed to drive others as far away as possible. Indeed, the section in which he sat was empty, the other library users clustered on the opposite side of the room.

We passed a man at another table writing feverishly in tiny script in a small notebook. He, too, wore clothes shiny with grime and the distracted air of one who has spent a lot of time wandering. I began to realize my son's experience with the local library was going to be a bit different from mine.

We found the children's section and passed a happy half-hour, amassing a modest pile of books that my son was thrilled to discover we could take home merely by presenting a small red card. I decided to leave by the back route. As we approached the elevator, we encountered a dwarf, dressed neatly in black, a well-worn bedroll by his side. He sat in a child-size chair, reading an encyclopedia.

"Terrible weather we're having, isn't it?" he said companionably.

I agreed.

"I like to sit back here," he said, with the air of one imparting a confidence. He gestured toward the main reading area. "There are so many strange people out there."