Some years ago, I was writing a sermon, and I had a half-remembered set of lines going through my head from a series of poems I had written twenty years before. At the risk of exhibiting my vanity, I thought that quoting those lines would cap the sermon's point off nicely. And I didn't have to say who actually wrote the lines, of course, I could just slip them in to make the point.
Well, after a long search through old files (I rarely throw anything away), I found the poems. They hadn't seen the light of day since my college years. I read them through, and thought: I can't use this. It's garbage.
You see, when I remembered the effect of those lines on me, I was remembering the very effect I had striven (in vain) to produce. The actual lines were terrible, and went back in the file. They will probably be discovered by my executor, who will promptly burn them (and good for him/her).
What a shame. The inner thought those lines attempted to convey still stirs me, but my skill is still not equal to my inspiration. So they will remain unpublished (and thank your lucky stars for that!).