Mending wall is a poem by Robert Frost. In this poem the speaker immediately tells us that something is amiss in the countryside. Something in the wide blue yonder does not like walls. He and his neighbor must get together every spring to walk the whole length of the stone wall that separates their properties, and to fix places where the wall has crumbled.
Then, our speaker begins to question the need for walls. He grows apples and his neighbor grows pine trees. His neighbor says that "good fences make good neighbors." The speaker becomes a bit mischievous in the spring weather, and wonders if he can try to make his neighbor reconsider the wall. His neighbor looks like a menacing caveman as he puts a rock into the wall, and repeats, "Good fences makes good neighbors."