Augustine of Hippo

"God placed cherubim and a flaming sword that moves"—this could be said in the one word movable—"to guard the way to the tree of life." Those who translate the Hebrew words in Scripture say that "cherubim" means in Latin "the fullness of knowledge." The flaming, movable sword means temporal punishments, because times move in their continual variety. It is called flaming because every tribulation burns somehow or other. But it is one thing to be burned until consumed, another to be burned until purified.