Roland A. Duerksen believes Shelley's poem is both celebrating the possibility and unobtainable nature of "true love," which is beyond romantic love, an entity that could, in a perfect world, be a driving, ethical force:
The upshot or ultimate realization of true love, because it has the qualities of unity, undiminishability and process, is its imparting to people the essence of liberty: "It overleaps all fence." (398)
But at this point the linguistic limitation rears its head in the poem and in our commentary upon it, and that is what Shelley laments at several points in the poem. He knows that images of the overleaping of fences and of elopement carry connotations of irresponsibility, escapism and even criminality--connotations that he does not at all intend to convey and that stand directly in the way of what he wants people to see about love. Realizing this inherent weakness of language, he, in the envoy, commands his "Weak Verses" to haste of the hearts of individual persons. (56)
Because of these limitations of language--reminds me of the story of the Tower of Babel from the Bible--pragmatic, legislative activism within particular, isolated contexts are essential. However, the unobtainable dream (I call it unobtainable) of the destruction of political, class, theological, etc. "fences" is an irrational yet pragmatic hope, an empathetic source providing the initiative to solve vexing problems within locally-contained spheres.
Dureksen, Roland A. Shelley's Poetry of Involvement. New York: St. Martin's P, 1988.