Main Theme of 'The Road Not Taken'

In the poem 'The Road Not Taken' by Robert Frost, the speaker reflects on a choice made at a fork in the road. The speaker contemplates how this choice will shape their future, emphasizing the importance of decision-making and the reflections that follow from it. The poem concludes with the speaker expressing a sense of ambiguity about their choice.

What is the main theme of this poem?