The fire that burns (cleanses) the earth is already kindled.
Anons have done much of this work of divine intent.
(Other translations have that verse: "Behold I come to send fire in the earth, and what would I if it be already kindled.")
>What other meanings might "Fire" bear?
Good question. It also seems to represent a translation into the future.
Often prophets would put ashes on their heads, which seems to mean recalling the past.
Both of these ideas are also somewhat the same - cleansing, and the future state of it being cleansed.