Jung on Paracelsus:

Many treatises define Mercurius simply as fire.

He is ignis elementaris,
noster naturalis ignis certissimus, which again in­ dicates his “philosophic” nature.

The aqua mercurialis is even a divine fire.

One text says that

"the “heart” of Mercurius is at the North Pole

and that he is like a fire (northern lights).

He is, in fact, as another text says, “the universal and scintillating fire of the light of nature,

which carries the heavenly spirit within it.”