Metaphors and similes attract us. All our clichés are built from them because they, at first, convey good visual images. We reuse them. We run them into the ground, beat dead horses in the process, and mix them up. Recycled too many times, the original image is lost.
It dawned on me (and I like the image of a sunrise popping out of my head) that in poetry we use metaphors to try to make meaning clear. And in prose we inject imagery to paint a picture. In both cases we want to get a message across.
The more I write (and read), the more I realize that there are times when a writer has to decide between poetry and clarity. Instructional books are all about clarity. If I try to evoke a mood or a moment with colorful images I may lose the reader in a swirl of confusion. The goal is to instruct. On the flipside, fiction that instructs is irritating. In his book The Art of Recklessness, Dean Young writes that poetry's task is to incorporate "…a humble transparency that adds nothing but clarity, the way a very clean window can add luster to a gray day it looks out on and frames" (7) and also "…all poetry must create some degree of impenetrability; otherwise the words are mere indicators of things beyond them and, therefore, immediately dispensable, disposable" (110). The words are the windows and are just as important as the meaningful view they frame.
How can a metaphor or simile, a visual understudy for something else, be clear? Muddied metaphors confuse us because we have to struggle to visualize them. One cloudy one is a friendship that has "ebbs and peaks" (rather than ebbs and flows or peaks and valleys). On the other hand, we can immediately see the image presented in the sentence "she moves through her day like a hummingbird." For the poetic image to convey clarity it has to be the precise, compact embodiment of the action or mood, a little anchor of understanding.