" - Oh, I'm from a different world we're pretty sure, there's no magic or anything and as best as people in my world can figure out it wasn't created."
"But anyways - so there's a finite amount of iron, right. You can turn it into a sword, you can melt it down and turn it into a plow, it can be ground into iron sand, it can be bound into ore or melted into magma, it can be alloyed into steel or separated back out - but it's always iron, just in different arrangements. And if you get into the really advanced, esoteric theories, physicists will say 'oh, iron didn't exist when the world came into being, it was formed in the furnaces of enormous stars from other elements, and with enough energy you could recreate that' - but there's still a finite amount of mass and energy, and no one has figured out how to create a pocket sun anyways."
"So Equivalent Exchange, or conservation of mass and energy, or that canticle - they apply more or less cleanly to iron, and pretty perfectly to the more abstract level of mass and energy."
"But what does it mean for a person to gain and lose something? What does value mean? If I create an iron spear from scattered atoms in the dirt, and then cast it away when I'm done with it - I haven't lost anything of value to me, but perhaps whoever finds that spear next will really need it, and would really value it. So more value has been gained than lost, even though the iron remains constant."
"And... What of joy?"
"Is the amount of happiness fixed? And what would that even mean, if it was?"