These last lines are a powerful summation of the poem’s emotional core, which is Herbert’s lament that Fortinbras’s way of being and Hamlet’s are forever irreconcilable. The idealist and the pragmatist are two different species: One admires the former and never hears of the latter. As Fortinbras knows, it will be he who does the work, who makes the filthy world that Hamlet rants about more clean. He will build sewers, and he will deal (one fears, harshly) with society’s problems—the prostitutes, beggars, and criminals—but he will be neither remembered nor admired.
Herbert lived much of his life in a time of political tumult and human agony: The Nazi occupation killed one of every five Polish people, a catastrophe which makes the catastrophe of Hamlet seem very small indeed. Having lived through a succession of idealisms turned awry and made brutal, Herbert may have acquired a real admiration for the literal-minded and modest medicines of a Fortinbras, who will “elaborate,” as he says, “a better system of prisons.”
Hamlet fascinates everyone, but those who help the world keep turning may very well be undistinguished or have, like Fortinbras, a quiet poetry of their own.