Let's say you're thinking of writing a story that you want to submit to various outlets for publication consideration. Let's say also that you have a bunch of stories that you've already self-published as free downloads on an online platform. Let us say a bit more, namely that there is a passage that you really like in one of those previous stories, something you believe would catch the eye of an editor at one of these places you want to submit to. Now, these places don't accept previously published stories (and yes, free ebooks that you put online yourself counts as "previously published"). In your opinion, would it be unethical to take a paragraph or a bit of dialogue and drop it into this new story (assuming, of course, that you could make it fit so that it felt organic)?