The speaker, a man on a ferry between Manhattan and Brooklyn, leans over a railing to look into the water below. He sees the clouds and the setting sun reflected there, and he addresses them as "you," as he will address many other things in the poem. He notes how all the business people and workers on the ferry appear "curious" to him. He thinks about the people who will make the same crossing many years from then.
He feels connected to a pattern larger than himself, and how the past and the future resemble each other. He praises the stuff around him as "glories."
Other people will make the same crossing as him and see the same things, like the sunset and the tides. These things will exist even in a hundred years.
Time and place cannot separate people, particularly when the speaker seems to have the power to project himself into the future. Speaking perhaps to future readers like us, he announces, "I am with you."
He gives examples of common experiences he has shared with his imagined reader, such as being part of a crowd or leaning against a railing on a ship. He begins to talk about the ferry crossing as if the reader has also had this experience. He paints a picture in words of the city and the other ships.
He says he is projecting himself into the future in order to tell us about this nice ferry crossing. Oddly, he talks about himself in the past tense, saying how much he loved the city. We're like, hey, you're not dead yet.
He points out how close we are to him. He's all, "What's a couple hundred years between friends?" Answer: not much. He describes the specifics of his life as if we had lived it, too. In case we thought he was this happy every day, he points out that he often has dark thoughts and has committed evil acts. Then, as if confessing, he pours out all the evil things he has done: lying, adulterous thoughts, and so on. He has to get some stuff off his chest.
Despite all these evils, people like our speaker. Young men in the streets know his name, and he's really just an Average Joe. He compares life to theater.
He suddenly gets up close and personal, saying how he could be watching us even as we are listening to him. And by the way, everyone who has ever lived is connected by some mysterious "necessary film." Not "film" like a movie – "film" like soap scum.
He says that nothing, not even the "Gods," could be as amazing as the view he has from the deck of the ferryboat.
Out of nowhere, and sounding like Don Corleone from The Godfather, he says we, the readers, have reached an "understanding" with him.
He starts ordering stuff around, which gives him an excuse to recap everything he has said about the ferry crossing. He basically says, "OK, everything, I order you to keep doing what you're already doing! Ship, keep crossing! Waves, keep breaking!" Sure enough, they do. He's a powerful fellow, this speaker.
He says that we know the soul only by all the things that make up the physical world, the "faithful solids and fluids" that bind us together. These things have been waiting for us to perceive them in the right way. We've let them get away from us in the past, but no more! We've got those tricky things in our grasp now, but we're not going to let them go. In the end, the speaker affirms that the physical world provides the parts that make up the spiritual world, including eternity and the Soul.