"This is the skeleton of a magic seal." Charlotte drew five circles with a different kind of thickness. The outermost layer was the second thickest, but the thickest line was located in the middle.
"The reason for this arrangement derives from the four things you need to put into the magic circles.
"First of all, what do you think is the first thing you need to put here?"
Nathan answered without hesitation. "Element."
Charlotte shook her head. "Element is the last thing you put into the magic circle."
"The flow of energy then."
"Indeed." Charlotte nodded this time. "To be more accurate, it's a conducting line. The reason for it is that this line is used to circulate the ena to the entire magic circle."