Board Thread:Questions and Answers/@comment-11935184-20160907061010/@comment-11935184-20171009072202

Hitsuji Mamoru wrote: Mercury (quicksilver) is one the three primary components of any material in Alchemy alongside sulfur and salt. Quicksilver represents the spirit (differing from the soul and body).

I'm not sure what's the link between magical energy and the spirit in the Nasuverse, but this might be the relation you are searching for. That's just a guess. it's because of that knowledge of Alchemy that is posible to make that connection with the magical energy in the nasuverse, as the world lets anything aknowledged by the people as "plausible" to be "posible"