The theme that is found in the poem and that was important in this century is that nature can be found in everything.
In this poem, the author compares the train to a wild horse and by using this comparison, the author conveys the train even if it is a manmade object can be similar to a natural object.
The underlying message of this poem is that nature can be found in everything even in manmade creations. This was also a popular theme since people of the 19th century were concerned about nature even with all the industrial development.
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