The theme of this poem is the view through the window of a moving train.
Explanation:
By reading this poem we can see how the speaker is describing the vision he has when observing the outside of the train, through the window, while the train is moving. The speaker demonstrates how he can visualize the smoke of the train, along with the whole landscape outside the vehicle, such as the mountains, the plains, the mixture of colors that the scene presents and the movement.
