Why are fern's parents worried about her?

an expression designed to call something to mind without mentioning it explicitly; an indirect or passing reference.

hello,

your answer is a) the metaphor suggests that the poetic themes are serious and dark.

collins is comparing the poem to a dark room. he is suggesting that the poems theme is serious and wants you to understand it. you don't need to understand the poet in order to understand the poem. you also don't need to move around while reading it. he is simply saying the poem has a dark and serious theme.

- i.a -