Stopping By Woods on a Snowy Evening
Whose woods these are I think I know.
His house is in the village though;
He will not see me stopping here
To watch his woods fill up with snow.
My little horse must think it queer
To stop without a farmhouse near
Between the woods and frozen lake
The darkest evening of the year.
He gives his harness bells a shake
To ask if there is some mistake.
The only other sound’s the sweep
Of easy wind and downy flake.
The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.
— Robert Frost (American poet, 1874-1963) Published in the collection New Hampshire (1923). This volume of Frost’s poems is a Pulitzer-prize winning collection.
corneliatrent 
Ah, Frost! The poet who once categorised free verse as playing tennis with the net lowered. There’s something wonderful about this poem, and it’s that double line at the end. Repetition is an opportunity to reconsider meaning, an opportunity for repositioning. Just think about a recitation of this poem where stress in the repetition is different from stress in the first, for example.
I think I’ve been surprised at how Frost’s images are very direct and seemingly simplistic yet startling visual.
In this poem the strength of the repetition of the double line at the end is something I haven’t thought about until you mentioned it — you’re right about how the repetition is a way to reconsider the meaning. Instead of mere redundancy it possibly is a reflection of how the poet’s “promises to keep” evokes a state of insomnia/worry so his miles to go before sleep is both the physical distance between the woods & his destination and the insomnia distance between wakefulness and rest.