It is so great to be riding in a subway car and look out the window at another subway car speeding along right beside yours. It is always going at very nearly but not quite the same rate. You can see it's riders through its windows but they are oblivious. Few if any look back at you.

So you look inside the windows as they move back and forth and the people sitting there are like a still life on film.

First they pass by as the other train goes faster than yours, but then it applies the brakes sooner so the film goes into reverse. You see each one again. Most look much as they had but a few have changed position. One couple has been chatting the whole time.

Nothing is stopping you from looking around at the people on the same car as you. Every day.

Perhaps it's because everyone in you own car stays fixed in space, relative to you, whereas those you see through the windows of another car float slowly by, but your fellow travelers are never so compelling as those you glimpse taking another set of tracks.