What are the themes and literary devices in Robert Frost's poem "Black Cottage"?

The "Black Cottage" (reproduced below) is a poem that appears in the book North of Boston, written by Robert Frost in 1915.The poem is written in blank verse, meaning it doesn’t contain a traditional rhyme scheme. Though there is no rhyme, Frost writes in iambic pentameter, which imparts a pleasing and conversational rhythm. Frost does not divide the poem into stanzas, rather he allows the lines to flow, much like a stream of consciousness. The poem is dominated by concrete imagery with no figurative language.The title is a literal description of the setting in that the narrator is visiting a cottage painted black. We might infer that "black" suggests that a normally domestic, welcoming place has become grim and deserted:

Set well back from the road in rank lodged grass,The little cottage we were speaking of,A front with just a door between two windows,Fresh painted by the shower a velvet black.

The point-of-view is first person, but Frost uses a second character, the minister, to supply facts about the cottage and its departed occupants which the narrator cannot directly observe. For instance, the widow who lived in the cottage had two sons who deserted her as they grew. Whereas, in older times, the woman’s sons would have never left her, but the offspring in this story do not hesitate to abandon their aging mother. Here Frost sees, in the modern generation, a fraying commitment to family:

That had gone out of it, the father first,Then the two sons, till she was left alone.(Nothing could draw her after those two sons.She valued the considerate neglect).

The minister also points out that the woman was a church-goer who adhered to the traditional rituals that younger people had abandoned. The observation points out that the collective acceptance of belief can no longer bind a community:

But suppose she had missed it from the CreedAs a child misses the unsaid Good-night,And falls asleep with heartache—how should I feel?I'm just as glad she made me keep hands off,For, dear me, why abandon a belief

At the end of the poem, the minister knocks on a wall and declares that bees live inside. The bees poke their heads out like a life-force springing from the rotting cottage. With that image, the sun shines through the windows and the mood gives way to hope:

"There are bees in this wall." He struck the clapboards,Fierce heads looked out; small bodies pivoted.We rose to go. Sunset blazed on the windows.
https://www.patheos.com/blogs/acatholicthinker/2014/03/robert-frost-the-black-cottage-the-truth/

https://zigzageducation.co.uk/public/synopses/1668-s.pdf