Bursting with mad joy Mary bounces towards the monsters.
Bissy: But Mum, why doesn't Mary turn into a monster herself?
Sofia: I deduced that anybody who's already at a maximum level of happiness is immune to the monster's happiness powers.
Mary's crazy play-fighting makes even the monsters hesitate.
Monster 1: Stop it!
Monster 2: We give up!
Monster 3: Don't pull our arms off!
Sofia: Lot's of actions aren't universalizable when you think about it. But making dogs super-happy can never be wrong! Thus I figured out the solution to the problem by using the categorical imperative.
Bissy: Thanks for the explanation...