"Thou art inexcusable, O man, whoever you are who judge, for in whatever you judge another you condemn yourself; for you who judge practice the same things." (Roms. 2:1)
So Frodo, by an act of compassion, saved himself.
But what struck me in particular about this was how Tolkien took the themes "You haven't seen him." "Now that I've seen him" and "I'm frightened" "I'm still afraid" and carried it from the beginning of the first book all the way to the beginning of the fourth book. I'm not a great literary critic, but to me this just seems astounding. And it's only one example. Tolkien just amazes me.
I read somewhere that Christopher Tolkien had a timeline that his dad did that had down to the minute of each day each thing each character did.