Thanks for reading, Emma. And no, it's not a dumb or silly question.
I don't think "Guard your heart" qualifies as a Biblical quote. The first time we heard it in this story was early on when Jonathan told Clark to guard his heart. Remember that Jonathan was (if possible) more devastated than Clark over Lana's death, and he's not healing very quickly. His reflexive response is to guard his own heart to keep from being hurt again, and he gives that same advice to his son because he cares.
Problem is, if you guard your heart too well, you might miss something you're not supposed to miss. Or you might substitute something else you think is safer than the thing you're afraid to risk.
Hope that clears things up. Next chapter will be up by the end of the week.
