Plotinos: Complete Works, v. 3 In Chronological Order,...

As to the other elements, could not water exist without participating in the earth? Air could certainly not be said to participate in earth, because of its penetrability. It is very doubtful that the fire contains any earth, because it does not seem continuous, and does not, by itself, seem to be tri-dimensional. True, fire does seem to contain solidity, but not of a tri-dimensional kind; it seems rather to be a sort of resistance corporeal nature214). Only of earth may hardness be predicated; indeed, gold, in liquid state, is dense; not because it is earth, but because it possesses density, and is solidified. It would therefore not be unreasonable that fire, apart by itself, could subsist by the power of the Soul which sustains it by her presence. The bodies of (certain among) the guardian spirits consist of fire.216