Short Answer 
The poem reflects the speaker’s experience of observing a rapidly changing landscape from a moving train, vividly depicting nature’s beauty, including mountains and plains. The dynamic motion of the train emphasizes the fleeting moments of beauty and change throughout the journey.
1. Observing the Landscape
The poem captures the speaker’s experience of looking out the window of a moving train. As the train speeds along, the speaker describes the rapidly changing landscape, offering a vivid portrayal of nature.
2. Visualizing the Scene
As the speaker gazes outside, he notes the different elements that come into view. He observes smoke from the train blending with the surrounding scenery, including:
- Majestic mountains
- Expansive plains
- A vibrant mixture of colors
3. Capturing Movement
The movement of the train adds a dynamic quality to the poem. It creates a sense of transience and change, as the speaker reflects on how quickly the visuals pass by, emphasizing both the beauty and fleeting nature of the journey.