A city at night can make a person feel very small, and that is the feeling at the center of this poem. The speaker watches crowds, buildings and endless routine, and feels overwhelmed. Their answer is to keep busy, as if work were an anchor against the tide. But the poem doesn't present this as a real cure. The night scenes, with smoke in the rain and sickly-white light, feel tired and a little unreal.
The turn comes when the speaker admits the buildings seem to be "trying to say something," and that they don't know what it is, any more than the buildings do. That honesty softens the mood. Instead of fighting the city's pressure, the speaker looks for a patch of green, lies down in the grass and stares at the dark sky. The ending trails off in an ellipsis, leaving a quiet, open feeling. The speaker seems to find relief in something vast and old, which makes human worries seem smaller and easier to bear.