In “Mending Wall,” it seems that the wall itself is in a constant state of equilibrium or balance. Even when parts of the wall crumble, from hunters or from ice, the speaker goes to repair the wall back to it’s initial state. So even when moments of excess that tear parts of the wall down, balanced is restored when it is inevitably fixed.
However, not everyone agrees that the wall should be there in the first place. This refers to both the physical wall (as elements keep tearing it down), but also the imaginary boundary people have between themselves and others. The speaker in the poem is eager to overstep boundaries, a threat to the equilibrium. Their thoughts about the matter is a form of excess, which is pushed against by the neighbour. The neighbour repeats “Good fences make good neighbours,” a sign that he wants to keep the equilibrium.
What’s interesting is that the two are opposites: the speaker is mostly in their mind, while the neighbour is described as very physical and actually verbalizes their thoughts. The two push against each other, in order to break or to contain. This is another example of balance: two opposite but equal forces against the other.
Neither the neighbour’s perspective nor the speaker’s perspective is right or wrong. They are simply two different views. However, like Jane McGonigal said in her discussion with Professor New, despite their opposing views, they still come together cooperatively in their goal to build a wall. It could be that Frost is saying that opposites can coexist together, only if they stay on their respective sides, or if they have a common goal.
In terms of the poetic structure, Frost largely uses iambic meter in “Mending Wall.” It has a rather steady cadence, which itself feels very balanced. When it does stray from iambic meter, he slips right back into it. He also often uses pairs: human hunters and the elements nature; rocks shaped like loaves and shaped liked balls; dogs and rabbits; pine and apples; thought and action. This reinforces that balance can be seen everywhere, and that balance is something that is constantly renegotiated.