What is the theme of poem, The Road Not Taken and how does the poet develop it?
It has become a common coined phrase - "The Road Not Taken" - as has " the one (road) less traveled" and Robert Frost's poem deals with the decision-making process and the consequences of any decision once made. The title suggests that the speaker feels wistful about what may have lay ahead had he chosen the other where he had "looked down... as far as I could To where it bent in the undergrowth."
The speaker is worried about what opportunities he may have missed but at the same time did not want to take the easy way out; hence, he considered one and "Then took the other."
The theme of choices and consequences continues to bother the speaker who is a little confused and is concerned that , after his initial analysis "the passing there Had worn them really about the same," indicating that, even though he has just made a decision, he is already potentially regretting it.
After his acceptance of his decision " I kept the first for another day!" he basically acknowledges that having taken the other path, there will be opportunities on that route that may lead him in a completely different direction - "Yet knowing how way leads on to way I doubted if I should ever come back." There is an acceptance in that but still a hint of regret as in later years he "shall be telling this with a sigh."
The speaker is resigned to the fact that there is no right or wrong decision in fact although the particular decision made will definitely make "all the difference." The reader is left to contemplate whether the speaker did make the best choice!