Imagery is descriptive language that is used to create a picture in a person’s head. This includes both figurative language and sensory details.
One way that style is used for meaning is through the use of figurative language. For example, the speaker talks about the “weakening eye of day,” as the end of the day, which is personification. Personification is a type of metaphor where something nonhuman, such as day, is compared to something human.
Another type of figurative language is a simile.
The tangled bine-stems scored the sky
Like strings of broken lyres (lines 5-6)
In this case, this is a simile because it uses the word “like” to compare the stems to strings of lyres. Both of these examples, and the others in the poem, create a picture in the reader’s mind.
Sensory language is also used to bring out images. Words like “crypt” and “sharp features” create a definite and creepy picture. Much of the poem uses these dark images.
Alliteration is when intial sounds are repeated, such as "His crypt the cloudy canopy," which also adds to this dark meaning.