More Meat
"Who do you think created that circle to begin with?"
"It was you?"
"Yes, after many trials and errors, having no knowledge in magic, not to even talk about spatial magic, I tried to create one myself and indulge in self tutelage. Of course, the result is what you saw, an obvious failure."
After spending tens of years trying to teach magic to himself, Eir was able to figure out something, but even then nothing worked, and it all led to constant failures. He ended up giving up entirely on using magic as he didn't see himself as gifted enough for it. In the end, the answer he sort came to him in time, and even then he just couldn't leave, as if he did, the demons would invade the earth once again, so he had to remain to keep them sealed.