He only says Good fences make good neighbors Spring is the mischief in me and I wonder.If I could put a notion in his head why do they make good neighbors? Isn't it where there are 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. And to whom I was like to give offense. Which theme does this excerpt from the poem Mending wall express?