The city is full of windows. More buildings, more stories, more rooms equal more panes of glass. The windowless room is a horror, which the laws aimed to banish from residential buildings: hence the city’s many airshafts and courtyards. Every New Yorker should be able to see light and air, even if the light is dim and the air is dirty. Modern office buildings achieve the same result by eliminating interior walls on their vast floors. The reason your cubicle foxhole does not reach all the way to the ceiling is not only to deprive you of privacy, but to enable you, with a crick of the neck, to look 20 yards and glimpse the sun dazzle off the windows of the office building across the street.

Whenever anyone can look out, someone else can also look in. Voyeurism is the most unavoidable sin of city life, unless it is exhibitionism. I have looked up from my bedroom desk, which looks out a window, and seen, not just water towers and pigeons, but a young woman taking a shower. It was one of those moments when you say to yourself: “Heavens.” Hadn’t she heard of curtains? But people who look in glass houses shouldn’t throw stones.

Animals are more often visible in windows than people. Birds in their cages have little choice but to stay put, though cats seem to favor a post on the sill. Dogs rarely show themselves; although they love car windows, perhaps the lack of motion in a city apartment bores them. For many years the townhouse in Greenwich Village that replaced the building demolished by Bill Ayers and his friends had a teddy bear in one of its windows. I think its costume changed with the seasons. It was a decorator’s idea which, happily, proved to be a passing thing, more passing, unhappily, than Ayers.

At night the windows of the city glow with TV screens. They wink in darkened rooms like the crystals in The Lord of the Rings in which, if you weren’t careful, you got face time with Sauron. From afar all you see are blocks of color, giving way to other blocks in a series of clicks; the sight gives new life to the expression “motion picture,” though at a long enough distance all the pictures are abstract. Sometimes it’s good to step back, way back, and see what an art form, or a timewaster, or something that is sometimes one, sometimes the other, looks like. If you were in the room, close up, you might fall under the spell. The lure of enchantment is unevenly distributed: My wife will sit in front of a program she wanted to see, and end up reading the newspaper; I find myself rooted by other people’s tripe. That’s why I never watch television, unless I’m on it, or unless it’s behind somebody else’s window.

The most poignant rooms are the empty ones. Since most of my window watching is done from the sidewalk, I look up at a lot of ceilings. The eye is drawn to light fixtures — circular old tubes, or long straight ones mounted between reflective baffles, or single bulbs held in mesh baskets like the ends of lacrosse sticks. The night lights in offices are softer than the night lights in stairwells. Janitors and people evacuating in an emergency will just have to shade their eyes. Yet most of the life of stairwell bulbs is spent shining on nothing. They also serve who only stand and glare. In schoolrooms you can glimpse maps of the world, still using those Mercator projections with huge Greenland and tiny Ecuador. In one neighborhood school, until rather recently, I could see George Washington by Gilbert Stuart, looking from the past — two pasts: the time in which he was painted, and the time in which it was thought needful to hang the painting. Other windows show structural details — pipes, or the underside of staircases. Every year, someone must go from floor to floor, room to room, painting them, or they would be covered with dust like fur.

The empty room, framed by darkness, is without drama — which means it might be the scene of any action. It holds the suppressed excitement of anticipation. Looking at empty windows is like the moment in a theater, after you have found your seat, and you turn to see the props and scenery of the first act. Who will sit on that chair? There is a coat rack — so someone will come in from outside. You think these thoughts even of the stripped-down sets of Our Town or Endgame, because you know the bareness will soon be populated. It is like the similar moment in a concert hall when all you see is chairs, with a few instruments too bulky to be sauntered in — double basses, kettle drums. Or perhaps all the stage holds is a piano. You study the mechanism of the pedals, or the way the light slides over its black curve. Sound will fill you in a moment, this is the quiet before. It is like first walking into a bookstore, and seeing the hard covers that co-op money has placed on the front tables, beckoning with their fashionable fonts and artfully clipped photographs. If they could speak, they would say “Buy me”; if they could speak well, they would say “Read me — someone has put years into this.” Looking at empty windows is like looking at women we will never speak to, much less embrace. Each one has a story, and it isn’t yours.

Down my block is a twelve-story building, shaped like an L. In the angle is a much smaller building. Either the small building had a taller predecessor, or the larger building feared one, because the walls of the angle are blank, except for three small windows, just below the roof. Two are on the shorter wall, one is on the longer wall. They look at each other and nothing. Edward Hopper couldn’t do better.