One should probably also consider this, from Robert Frost's poem "Mending Wall": Before I built a wall I’d ask to know What I was walling in or walling out,

One should probably also consider this, from Robert Frost's poem "Mending Wall": 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 offence. Something there is that doesn’t love a wall, That wants it down.