How does Donne use metaphor in the poem's second stanza?

In the second half of the poem, the speaker uses extended metaphors to effectively remove the lovers from the earth. The lovers now exist both as saints and as immortal beings entombed in poetry itself. In the fourth stanza, the speaker says: "And if unfit for tombs and hearse / Our legend be, it will be fit for verse; / And if no piece of chronicle we prove, / We'll build in sonnets pretty rooms" (29-32). Here, the speaker uses the Italian translation of the word "stanza" (meaning "room") to suggest that the lines of poetry itself are a place where people can dwell, immortalized. This self-referential element of the poem is consistent with Donne's earlier erotic work in which he argues that lovers are united, physically and spiritually, by the crafting of verse.