This poem is written in the great heroic tradition: each line is iambic pentameter, consisting of five two-syllable "feet", of which the second syllable is usually emphasized. These lines are arranged in pairs or couplets. In each pair, the last syllable rhymes. There is only one exception to this rule, on line 49, where a third rhyming line is added to a couplet.
Behn's choice of heroic pentameter is not a coincidence. She selects it to deliberately evoke a sense of tradition and epic poetry. Indeed, she begins the poem as all the epic poets of the ancient Greek and Roman classical tradition did, with a speech to the Muses. She makes reference to the "little gods" or Cupids and speculates that, in the court of Augustus Caesar, the deceased John Wilmot would have received even greater fame and glory.
Fulsome praise in a poetic eulogy is not unusual. Behn, who came from unknown and probably modest origins, would ordinarily not have crossed paths with an aristocrat like Wilmot or received an education that featured lots of poetry or classical mythology. Yet at some point in her life she acquired enough of a classical education to not just make classical references, but to slyly subvert them. Instead of invoking the Muses and pleading for inspiration, Behn commands them to mourn the untimely death of a great wit and literary luminary who inspired a new tradition of irreverent satire. She asserts that the dead Rochester dispensed inspiration as though he were himself a Muse, with godlike generosity and leadership. This claim had a basis in fact: Rochester mentored many writers, actors, and even actresses by sponsoring them and drawing attention to their work. Then, as now, celebrity endorsement was a great way to start a career in the performing arts.
The poem is broken into five stanzas, not of regular length. Each stanza ends with an injunction to mourn. The first stanza is directed to the Muses, followed by the "Youths" or the young men of the Court, and the "Beauties" or the women with whom Rochester dallied. Subtly, Behn acknowledges Rochester's reputation as a libertine, but she places the blame for his untimely death (believed to be a combination of alcoholism and venereal disease) on the women Rochester loved. With the fourth stanza, Behn returns to her original divine theme, addressing the "little gods" or manifestations of Cupid. This works because she segues in from the topic of love. Yet the Roman gods addressed in the fourth stanza lead to a discussion of Roman tradition in the fifth: Behn asserts that, had Rochester lived in the age of Augustus Caesar, he would have been elevated to godhood as a person who had greatly benefited the Roman people or the Roman state. This assertion can be construed as an extremely subtle criticism of the way he'd been treated by the King: banished repeatedly from the Court for drunken shenanigans and violent behavior. To the King and to England, Rochester's wit and literary talents only partially compensated for his egregious and disrespectful behavior. In this poem, Behn suggests that a greater ruler-- Augustus Caesar-- would have been magnanimous enough to overlook Rochester's faults and simply reward the positive aspects of his character.
Overall, this poem is both a blatant attempt to gain favor with Rochester's family and friends by presenting him in the best possible way, and a subtle criticism of royal policy and decision making.