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This poem is a metaphor of life. It tells about making choices and taking the right path.
1- The poet is describing a fork in the road. The 'yellow wood' suggests it is autumn season
2_3- The poet wants to go down both roads at once, but realizing that it is impossible, he dicides to choose one. Thus antethesis is used here.
4_5- He is thinking hard about his choice. He stares at one road, seeing where it goes but he can see only up to the 1st bend.
6_8-He looks at the other road and thinks it would be better as it hasnt been walked veery much. The word wanted means 'locked'. Thus alliteration is used.
9_10- He changes his mind and says both the roads are same in appearence.
11_12- Both the paths have been covered by leaves. They havent turned black by crushing them.
13- The poet decides to take the 2nd path. He kept the 1st one for later.
14_15- His hopes to come back and try the other path may be foolish as one path leads to another. He doesnt know whether he would come back.
16_17- (We jump forward in time) ZThis line is very important. The 'sigh' can be a sigh of satisfaction or a sigh of regret.
20- 'A difference' could either mean success or utter failiure. The poet is just saying that the choice he had to take was an important one.