What are the devices used in stanzas 3 and 4 of "The Darkling Thrush"?

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mwestwood eNotes educator| Certified Educator

Stanza three of Thomas Hardy's "The Darkling Thrush" marks a break from the first two stanzas' tone of patent despair.  Suddenly,

In a full-hearted evensong 
Of joy illimited; 
An aged thrush, frail, gaunt, and small, 
In blast-beruffled plume, 
Had chosen thus to fling his soul 
Upon the growing gloom.

This thrush may well be a metaphor for the spirit of Thomas Hardy himself as he wrote this poem in 1895, the year that his novel Jude the Obscure had been burnt in public censure. Criticism of this book as well as Tess of the d'Ubervilles convinced Hardy to turn to writing poetry instead.  Thus, the "blast-beruffled" thrush may certainly represent Hardy's soul that finds the "growing gloom" as the objective correlative for his uncertain future and that of the forthcoming century upon which he casts his talents as a poet.

In stanza four there is a paradoxical situation that has been initiated in stanza one with

The tangled bine-stems scored the sky 
Like strings of broken lyres,

lines that suggest that there is no correlation between Nature and man, and there is, in fact, a senselessness to nature, although man has tried to find in it reasons for his being.  In fact, the Romantics of the new century to come believe in Nature as a reflection of the spirit and as a path to spiritual development. But, Hardy finds no such inspiration from nature. To the speaker, the senselessness of the darkling's song amid the nineteenth century's pain and suffering is paradoxical to the personified "Hope":

Some blessed Hope, whereof he knew 
And I was unaware.

While moving from the despondent tone of the first two stanzas to one that is more upbeat, stanza three, nevertheless, sets up the senselessness of a nature that is connoted with Hardy's diction, as for example,  the "blast-beruffled" bird that yet breaks into a 

full-hearted evensong 
Of joy illimited

providing Hardy no respite from his despair as he realizes there is no correlation between nature and the human spirit, an idea that is conveyed through the poet's use of words such as "darkling," spectre-grey," "illimited," (ill-suggestive of the negative), "trembled"--connoting momentary action) as well as his tone.  Also, critics say that the use of iambic tetrameter rather than the conventional pentameter creates some tension in the lines that provides the poem "energy and emotional depth" that is counter to the despairing tone and the senselessness of nature.