Date: w. 350 B.C.

"This is what led Democritus to say that soul is a sort of fire or hot substance; his 'forms' or atoms are infinite in number; those which are spherical he calls fire and soul, and compares them to the motes in the air which we see in shafts of light coming through windows."

— Aristotle (384-322 B.C.)

Date: 1632

"Looke as it is with a Gold smith that melteth the metall that he is to make a vessell of, if after the melting thereof, there follow a cooling, it had beene as good it had never beene melted, it is as hard, haply harder, as unfit, haply unfitter, then it was before to make vessell of; but after ...

— Hooker, Richard (1554-1600)

Date: w. 1755, 1777

"But admitting a spiritual substance to be dispersed throughout the universe, like the ethereal fire of the Stoics, and to be the only inherent subject of thought, we have reason to conclude from analogy, that nature uses it after the same manner she does the other substance, matter."

— Hume, David (1711-1776)