It is important to understand first what imagery is in poetry, so that we can look for it and reflect on it. Imagery is literally the elements used in a poem that seek to touch the senses and emotions of a person so that they can connect with the message of the text. It helps a reader to see in his/her mind what the author is painting through his words. Words, then, become almost like the brush of a painter and give the reader the image of what is being portrayed. In this passage, the imagery is a dark one, of despair and sadness. It paints through the word disease, which is repeated several times, a picture of devastation that affects all the levels of life within the speaker´s world. And then, the imagery gets even darker, when the poet uses words like deadly pestilence and claims it to be as powerful as a god, something that cannot be turned away or run from, which devastates the cities and countryside alike (this is known by the image offered when the poet mentions the House of Cadmus). In the end, the result of disease comes to be even darker, leading to death decay and hell itself, where even more pain awaits, this underlined by the use of words like Hades, and groans and howls.
Assuming that you're referring to the Flvs english 1, the one that you need to think bout throughout unit 1 is : Future possibilities. Most of the topic in this unit talk about future possibilities
