Thanks for taking the time to check it out. One point as I read it is that the wall is unnatural. Nature itself rises up to destroy it each year, and it must be repaired. When they build and rebuild the wall, they're fighting the natural order and nearly resorting to magic, (use some spell to make them balance) which in poetry often symbolizes total dominance over nature. But it only works until they look away. Then you have the two characters: one that follows what he's always done (repeating good fences make good neighbors and never really questioning it, just accepting it as the truth as his father did and one that senses that something incorporeal and almost imperceptible that wants the wall down (call it nature or the natural order of things or a natural ideal). The poem ends on a sad note. As the narrator is having this transcendent moment where he realizes that the wall is unnecessary and questioning its existence entirely (I'd ask to know what I was walling in or walling out and to whom I was like to give offence), the neighbor appears like a savage living in darkness. When presented with the opportunity to think for himself and question the way things have always been done, the neighbor rejects it and sinks into his father's words (which he believes he thought of by himself). So you have the wall and what it means, you have two opposite characters one their sides of the wall, and you have a kind of growing versus stagnating binary going on on either side of the wall. That's how I see it anyway