Twilight: You see this, Spike?



Spike: This bright, shining light? Yeah?



Twilight: This, Spike... is your soul.



Spike: My... soul???



Twilight: Yes. You see, a soul is the very culmination of somepony's being. It's what makes you, you.



Spike: It sure is twinkling a lot... Is that good, or bad?



Twilight: Good, obviously! *giggles* The brighter a soul shines, the more compassion they have in their hearts. And yours is one of the brightest, shiniest souls I've seen!



Spike: It is??? Well, how much does your soul shine, Twilight?



Twilight: I don't know. I never checked... but it's not a competition, Spike. The fact that a soul shines at all is a sign that somepony is capable of loving, and being loved. It's the best omen of all, because it proves beyond the shadow of a doubt that you're just as alive inside as you are outside.



Spike: Wow...



Twilight: Friendship is the spark that makes that light shine ever brighter. ...But a spark is just a spark. In order to truly unleash the care in your soul, we need to keep building and building on the friendship's we've forged... and look out for chances to make more. Everypony's soul is sacred... even the ones that the Nightmare Forces have tainted, or barely shine at all anyway. The more somepony's friends care for them, the stronger their soul becomes.



Spike: Oh, my Luna... So... what if we meet somepony that doesn't have a soul?



Twilight: *expression twists to unease* O-Oh... Um... That's... That's almost never the case... But without a soul, somepony wouldn't be able to feel joy, sadness, empathy... ANYTHING, really. There'd be nothing stopping them from doing as they desire. They'd be literally EMPTY inside. They'd just be a husk, acting on instinct alone...



Spike: Twilight...



Twilight: Hm?



Spike: Is... Is Kamek soulless?



Twilight: … Sometimes, I wonder... *frowns sadly*