""Because they are made of magic, monsters' bodies are attuned to their SOUL. The damage a monster receives from an attacker is dependent on both the monster's will to fight and the attacker's will to hurt. This inadequacy is because monsters are mostly made of magic, which in turn makes them attuned to their SOUL.
Humans, with their physical forms, are far stronger than us. "While monsters are mostly made of magic, human beings are mostly made of water. just to equal the power of a single human SOUL.''" - Ancient glyphs in Waterfall It would take the SOUL of nearly every monster. Template:Quote''Humans are unbelievably strong. Monsters are by far weaker than humans, both in physical combat and regarding the strength of their SOUL. " - Book 6 (from the left) in Snowdin Library" After all, humans have proven their SOULs don't need these things to exist. But the absolute nature of "SOUL" is unknown. This is what people say monster SOULs are made of. It is even said that monster SOULs are made of love, hope, and compassion. Despite the negative implication of the word "monsters," monsters in Undertale are not an evil species. After The War of Humans and Monsters, monsters moved to the Underground from the Surface. King Asgore Dreemurr rules all monsters in the Underground. Every character encountered in the game besides the protagonist, the fallen human and Flowey is a monster. They dwell in the Underground beneath Mount Ebott, while humans and other races/species live on the surface beyond the Barrier. Monsters are a very diverse race in Undertale. For a list of all known monsters, see NPCs and Category:Characters.