I want to quickly mention how important it is to ride in the front or rear of the subway from time to time, and in conjunction how important it is for the front and rear cars of the subway to have nice large windows through which you can watch the tunnel go by. For a long time in my childhood the pleasure of riding in the front or rear of the subway was one I would seek out. The old subway cars were the best for it, since their windows were large; the newer cars on the 2 or 3 trains had very small windows that were far higher than I could see as a child, and I would need my Dad to hold me up to them so I could get a proper look. It would cause small arguments: standing on the platform waiting for the train (and many stations didn't have subway clocks so you were really waiting) my parents would want to stand at the most efficient spot for whatever stop we were going to, so that when the doors opened at our destination we could step right off the train and be at the turnstyles already. I believe this is another very important skill, as it requires a deep familiarity with and appreciation for the subway system to get right consistently. I, however, would always advocate for the front or rear of the train, regardless of how inconvenient it would make our exit, because I loved so much to look out the windows. As an adult, my tastes have matured and my humor has mellowed. Most of the time I will pick the most efficient door for my ride, counting relative to the front, end, or zebra. I know how many doors each type of train car has, and at what stops the express and local trains don't line up exactly and force you to offset your calculation. There are times, however, when I will still seek the extremities of the train for the rare pleasure of a proper look out the window. I feel this carries value both as a source of entertainment and as a source of spiritual growth. So often the subway is like a magic portal: you go down into its mouth, down the stairs or maybe an elevator until you have no sense of how deep underground you are; you get on the train, which lurches and swings so that you get some sense of when you are turning left or right, but for the most part the ride is smooth and from the side windows you can only watch the lights stream by; and finally you get off, and the world resumes and you are suddenly in a completely different part of the city. This it the beauty of the subway, as it gives you time to sit and think, existing a little bit away from the physical plane. Yet to every thing there is a season, and sometimes it is also important to find your feet, and to understand the space you move through so the subway is a little more real and a little less magic. This is why they put windows at the front and rear of the train. From these windows you can understand the subway tunnel as a physical space, and one that is continuous and real, connecting point A to point B with no magic except human ingenuity. You can see the lights change color as the signals let the train pass by or bring it to a stop; you can also see the faint light of the station far ahead and know that you are approaching even before the brakes engage. At stations that are all bunched up, such as 18th street on the 1, you can see the light of the next station even before the train pulls away from the platform, and you really understand where you are and where you're going. In the dark tunnel the colored lights twist and shimmer and the third rail will sometimes spark, and through the dirty glass of the window it is a bit like looking into a kaleidescope. I once tried to make a shader to replicate the effect, similar to Martijn Steinrucken's "The Drive Home" (https://www.shadertoy.com/view/MdfBRX) but found my skills not quite up to the task. I will have to try again, so people who don't live in the city can experience some fraction of this pleasure. For those who do live in the city, for your own health, look out the front or rear windows of the train from time to time.