Brooks and Warren work hard for the money. Um, we mean, they work hard to define poetry. In this text, they say a poem isn't some bundle of "poetic" things, or just a decorated box that holds some great moral or truth:
Certainly it is not to be thought of as a group of mechanically combined elements—meter, rhyme, figurative language, idea, and so on—put together to make a poem as bricks are put together to make a wall. The relationship among the elements in a poem is what is all important […] If we must compare a poem to the make-up of some physical object it ought not to be to a wall but to something organic like a plant. ("Introduction," 16)
What do Brooks and Warren mean when they say a poem isn't a "bundle," like a bunch of bricks? Why do they argue it's about the "relationship" among the elements?
The New Critics were super attentive to metaphors and figurative language. So why would they talk about how a poem is or isn't like a wall or a plant? In each of these metaphors, what's the relationship of the part to the whole?