In general, alliteration helps give the poem its unique music (along with other devices like consonance and assonance). The poem is, in a way, about itself—the speaker meditates on the act of writing poetry (how it happens and what it feels like) through writing a poem. Devices like alliteration help mark out that this is specifically poetic writing.
The first example of alliteration in the poem comes in the very first line: "midnight's moment." Apart from signalling that this is language organized through sound as well as sense (in other words, poetry), this could be an allusion to Gerard Manley Hopkins, one of Hughes's key influences:
- The latter poet's most famous poem, "The Windhover," opens with a similar construction ("I caught this morning morning's minion").
- As this is a poem about writing poetry, and appears in Hughes's first collection, it's possible that this is a little nod towards one of his poetic heroes!
Later in the poem, alliteration mirrors the twitchy movements of the fox (which, again, represents thought and inspiration). The /d/ sounds in lines 7 ("deeper" and "darkness") and 9 ("delicately" and "dark") and then the two /t/ sounds of "touches twig" in line 10 construct an image of an animal feeling its way instinctively through its environment. The /d/ sounds, which are quite soft and dull, also have a hypnotic quality that signals the speaker's deepening journey into his own unconscious mind.
In the third stanza, alliteration creates a contrast between the fox's shadow and its body. The shadow (perhaps standing in for poetic doubt) is reluctant to move forward—it is "lame" and "lags." These soft, tentative /l/ sounds contrast with the confident tone of "body" and "bold" in line 16, subtly supporting the poem's argument that poets, like foxes, should trust their intuition and primal instincts.
Alliteration can also sound surprising and sudden, as in line 21's "sudden" and "stink." This is the moment that the thought fox enters the speaker's head; inspiration arrives and the speaker's creation lives on the page. The plosive /p/ sounds of "page" and "printed" in the last line have the same effect, ending the poem on an emphatic note that boldly claims that the speaker's work is done—and that something is now alive (a poem) that until moments ago didn't exist.