The dominant theme of Thomas Hardy's work, both prose and verse, is pessimism. Hardy sees not so much a hostile outside world but one of randomness and unpredictability which nevertheless foil man's best laid plans.

In "The Darkling Thrush" the bird represents that part of life that resists this reality, as Hardy views it, and still sees hope and joy in the world. The setting described by Hardy could not be bleaker:

I leant upon a coppice gate
When frost was spectre grey,
And winter's dregs made desolate
The weakening eye of day.

Though the bird resists acknowledging the darkness of the outside world, it is not as if it personally has anything to be happy about. The thrush itself is old, frail and gaunt, with "blast-beruffled plume." In fact, the title of the poem indicates that the thrush, despite its apparent happiness—that it sings its song as if all is well—is itself a victim of the bleak outer world, the vacant winter landscape described by Hardy, in being the darkling thrush. The bird nevertheless stands for the capacity that all of life on earth possesses to continue, to go on fighting against the odds no matter how dark the situation.