I sometimes have a thought pop into my head, a one-liner that suddenly makes sense to me. It seems to be a direct quote but it must be a distillation of something I read. Reading Keynes, for example. He doesn't usually write one-liners. So I wake up one morning and say "Oh, Keynes said you can only either spend money or save it." And in my mind, the
you can only either spend money or save it part is what Keynes said -- his words, not mine. And that's how I think of it.
And I've had a couple times when I went looking thru
The General Theory for the particular phrase. So I could document it in my writing. Looking till my head hurts, but not finding.
Doesn't mean that the exact phrase is not in the book. But by the time my head hurts, when I give up the search, I'm convinced that the exact phrase is not in the book. At that point, I have to think that those particular words are what Keynes said, but my version of it. I don't know if that's correct, but it's what I have to think in order to proceed.
After that, I might say something like
Keynes said you can only either spend money or save it. No quotes, so it looks like I'm paraphrasing him. But attributed to Keynes, so I'm not stealing the words.
It's a compromise that lets me move on to the next sentence.