The speaker in "Mending Wall" describes the yearly practice of mending the wall as a sort of "out-door game" he plays with his neighbor. Although it is the speaker who reaches out to his neighbor to initiate this year's repairs, the neighbor takes the maintenance of the wall far more seriously than the speaker does. For the speaker, the wall is simply something that is maintained out of habit but doesn't need to be. After all, there is no particular reason why an orchard should be separated from a pine grove by a wall. But the neighbor is committed to the idea that there should be a wall between the two properties.

In the same way that the speaker figuratively imagines that the gaps in the wall may have been made by magic, perhaps by "elves" or some other mysterious spirit that opposes the wall, he describes the act of mending it as having some magic in it, too. As he and his neighbor walk down the line of the wall, they pick up the boulders that have fallen down on each side and return these to the wall. Sometimes, however, the boulders seem so round that it takes almost a "spell" to make them balance again. The wall's integrity is precarious, but the force of tradition helps them to rebuild the wall every year, just as another force tears it down.