Last week, I was looking with writer friend at a draft of a story she had written. It was typical of her writing--complex, deep and beautifully crafted, but she wanted me to cast my English teacher eye over it and see what I could find. I couldn't find much, but her use of "needle in a haystack" immediately struck me as out of keeping with beauty and grace of the piece.
I knew what had happened. She was writing along and needed some figure of speech to convey finding something rare,something that was difficult to come by. Still, the metaphor stuck out like a sore thumb (ha ha) (I know, that was a simile. Close enough.) and did not suit the warm and organic subject and tone, which was about nature and our place in it. The writing also had a motif of gold running through it.
To my way of thinking, metaphors need to be as original as we can make them, consonant with the tone of the writing and possessing a certain resonance. The needle didn't work on all three counts.
Later on, I thought of the Pearl of Great Price from the New Testament parable as a less used metaphor and one that carried forward the motif of treasure, but I didn't like the hardness of the pearl, and the color didn't go with anything else. I emailed my friend anyhow, and she replied, writing that she had settled on a four-leaf clover as the right figure of speech, and it was. It was original, fit the warm and organic tone and resonated with the treasure and nature motif. It was a winner.
All this seems like a lot of angst over a phrase, but I would suggest that such attention to a word or phrase or sentence is what makes our writing sing. In this case, two experienced writers wrestled with coming up with exactly the right figure, and it paid off.