The primary theme of “The Darkling Thrush” is the despair of the modern temperament. Hardy describes in lyrical, descriptive detail the dying of the old world, but he cannot positively replace the dying with the new. Something is over, all is changed, civilization has decayed, and he does not know what will replace it. In “The Darkling Thrush,” Hardy poses one of the central questions of the modern age and reveals himself as a significant voice of the early twentieth century.
Hardy the modern poet is an isolated man. He has lost his connection with those nineteenth century people who are inside by their household fires. They are connected with one another, and with the natural cycle of death and rebirth, but Hardy, the twentieth century persona, is alone in the cold, surrounded by images of death. He may yearn for that simpler, truer world, and he may seek to recapture something that is lost by using the form of folk themes, but that old century is dead, and the outlook for the new century is bleak indeed.
Hardy saw traditional agricultural society decaying, the earth destroyed by industrialization, and in “The Darkling Thrush” he clearly reveals that he cannot believe in a note of hope. He finds “so little cause for carolings” that he cannot picture the new century or describe it for the reader. Hardy is “unaware” of any hope for the future.
With his tale of the “darkling thrush,” a thrush of evening rather than morning, Hardy rejects the Romantic themes of the nineteenth century. While the song of the thrush is the force that crystallizes his fervorless spirit, Hardy’s thrush is aged, “frail, gaunt and small,” not symbolizing new life but belonging to that dying old century. Even after hearing the thrush’s “full-hearted evensong/ Of joy illimited,” Hardy’s depression is lifted only as far as a state of puzzlement. He comes into the new century unable to believe that even the thrush, that representative of nature, can have a reason to hope.