What is the symbolism used in the poem "Mending Wall" by Robert Frost?

Major SymbolsThe major symbols in "Mending Wall" are the stone wall and the "fences" spoken of by the neighboring farmer: "He only says, 'Good fences make good neighbours.'" Each slightly different from the other, both symbolize the artificial and deliberately constructed barriers humans seem inevitably to erect between themselves.
There are two attitudes toward these barriers conveyed in the poem. The first is that of the speaker, who seems to have a tolerant, amused attitude, although, being the poetic soul he is, his amusement is soon off-set by contemplative musings. The second attitude is that of the neighbor, who seems to have a serious, dutiful, no-nonsense attitude, which remains undeterred when the speaker tries to engage him in riddles about the superfluity of walls:

Spring is the mischief in me, and I wonderIf I could put a notion in his head:"Why do they make good neighbours?...[...]...I'd ask to knowWhat I was walling in or walling out,..."

Another important symbol is the twice-said "Something there is that doesn't love a wall...," which is philosophically off-set by the twice-said "Good fences make good neighbours." Frost's metaphysically speculative observation of the "something" that doesn't love a wall can be taken literally as illustrated in the second line, which describes ground heaves of winter's frozen earth [today in New England, brightly colored strings are stapled to utility poles warning drivers of "Ground Heave," which can buckle roads up into ridges one or even two feet high]: "That sends the frozen-ground-swell under it,...." The symbolic meaning of this "something" relates to the paradoxical desire in humans for psychological and emotional intimacy even while erecting barriers to such intimacy: "something" is the hesitance to be known paradoxically opposing the desire to be known.Secondary SymbolsThere are secondary symbols in "Mending Wall." Some are "spills" and "gaps," paradoxically symbolizing either (a) damage leading to vulnerability, such as hunters (symbolizing careless, destructive people) in pursuit of symbolically innocent rabbits, or (b) openings leading to opportunities, such as are created by "something," perhaps an inner "ground-swell" of psychological expansion. Another symbol is "spring mending-time," symbolic of a cyclical opportunity for renewal that continually offers new chances at the psychological and emotional intimacy desired (and, from the mending wall neighbor, continually resisted). Another significant symbol is the place, a specific section along the neighbor's wall, where there is no need for a wall: "There where it is we do not need the wall." This place symbolizes a recurring opportunity between people to find the desired connectedness, perhaps in ever-present social situations in which renewal of opportunity is present on a recurring basis.
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