Something there is that doesn't love a wall,
That sends the frozen-ground swell under it,
And spills the upper boulders in the sun;
And makes gaps even two can pass abreast
The above selection of the poem shows how impersonal the wall is. There is no humanity associated with this object, nor is there any emotion attached to it. Even thought the object has no emotion itself, there is emotion directed toward it as we see in line 1 of the poem. There is something out in the world that doesn't like this wall. Not only does this relate the author's feelings about how it keeps objects separated, This feeling of animosity has gone so far that something has gone as far as to destroy sections of the wall.
I have come after them and made repair
Where they have left not one stone on a stone,
But they would have the rabbit out of hiding,
To please the yelping dogs, The gaps I mean,
The author goes even further in his description of the emotions directed at the wall, and explains that other dislike the wall as well. Although they dislike it because it is helping to hide the quarry they are after. The hunters express this dislike of the wall but physically destroying the wall, they tear it down even though it is not their wall. This goes a long way at letting the reader understand that this poem is also about relationships between people. Often times others will attack a person to get something they want with little to no regard for the person that is being attacked.
But at spring mending-time we find them there.
I let my neighbor know beyond the hill;
And on a day we meet to walk a line
And set the wall between us again.
This little wall goes a long way in effecting the author's relationship with his neighbor. They go out of their way to make repairs to this small stone wall, that really has no purpose other than to keep their lives separated. This purpose may seem like a small one but both individuals meet to make sure the wall stays standing and keeps their lives separate. They are meeting and interacting only because the thing that makes them comfortable with each other has fallen in to disrepair and needs to be erected again.
My apple trees will never get across
And eat the cones under his pines, I tell him
He only says, "Good fences make good neighbors."
The author is trying to get past the barriers that people erect between themselves and the rest of the world in the above section. He tells his neighbor that even without the wall their lives will never interact with each other's. Even with his insistence the other man makes sure that the wall will go up again. He is going to do everything he can to ensure that every facet of his life is separated from that of his neighbors.
Why do they make good neighbors? Isn't it
Where are the cows? But here there are no cows.
Before I built a wall I'd ask to know
What I was walling in or walling out,
Here the author is confused because once again he is trying to get past the barriers that keep people separated. The author doesn't feel like there is anything that needs to be separated, he would be able to understand it if there were some sort of object that might cross into his neighbor's world, but there is no such object. The only thing to keep separated is the two worlds them selves.
He will not go behind his father's saying,
And he likes having thought of it so well
He says again, "Good fences make good neighbors."
Once again the neighbor's grasp on an old tradition and saying are all that justify the wall being in...