This poem is about mankind's loss of innocence and consequent fall from grace, and it uses the expulsion of Adam and Eve from the Garden of Eden as its reference point. In the opening stanza, which is a quatrain, there is an alternating rhyme scheme, whereby the first and third lines rhyme ("death," "breath") as do the second and fourth lines ("time," "slime"). In the second stanza, also a quatrain, the rhyme scheme becomes less regular. In the second stanza, the first and third lines do not rhyme ("Eve," "makes"), but the second and fourth lines do ("serpent," "innocent"). In the third stanza and all subsequent stanzas, there is no rhyme scheme at all.
In fact, from the third stanza on, the quatrains become tercets (except for the penultimate stanza, which is a one-line stanza), and the syllabic meter also become much less regular.
This disintegration of the rhyme scheme in the opening three stanzas, along with the altered stanza lengths and syllabic meter, mirrors the loss of innocence which is the central theme of the poem. The rhythm and structure of the poem break down to reflect mankind's gradual loss of innocence. The broken rhythm and structure also possibly reflect the broken relationship between mankind and God, consequent of Adam and Eve eating the forbidden fruit in the Garden of Eden.