In my previous posts, I wrote sentences like these:
Here is the sentence from C. S. Lewis' The Magician's Nephew.
Here is the piece from a video game.
Then I was citing either one or several sentences from the book/game.
I really don't know whether the definite article was correct there. The sentences aren't the only ones present in the book/game, but, on the other hand, they're particular -- they're the sentences which I was going to talk about.