Comment on the importance of the landscape and setting in the poem "The Darkling Thrush" by Thomas Hardy?

The landscape or setting in "The Darkling Thrush" is all important for both setting the tone of the poem and highlighting the contrast Hardy hopes to make in the last stanza.

For the first two stanzas, Hardy presents the reader with a landscape that is unrelenting cold, bitter and bleak, populated with images of death. The frost is gray, not white, and "winter's dregs [remnants]" are "desolate." Nobody is out in this miserable, harsh, ugly landscape--everybody is gathered around their fire inside.

By the second stanza, the landscape is likened to death and a corpse: it is a "crypt," "shrunken hard and dry," the wind a "death-lament" and the spirit of the setting "fervourless" or lifeless. At this point in the poem, the reader could hardly feel more depressed. 

Thus, the introduction of the thrush into this desolation in stanza three is all the more of a contrast. Its song "of joy," even though the bird too is old and frail, is all the more startling given the dead landscape in which it sings. We wonder, along with the poet, how the bird can be "caroling" with such "ecstatic sound" in such a barren, forlorn setting. The poet feels alienated from such "blessed Hope," given the evidence of his senses, and leaves the reader also wondering how the bird can be so happy.