"The man has now become like one of us, knowing good and evil. He must not be allowed to reach out his hand and take also from the Tree of Life and eat, and live forever. So the LORD God banished him from the Garden of Eden to work the ground from which he had been taken. After He drove the man out, He placed on the east side of the Garden of Eden cherubim and a flaming sword flashing back and forth to guard the way to the Tree of Life."
Guard = sāmar =
Keep watch/ keep guard/ protect.
To keep within bounds/ restrain.
"So God expelled them from the Garden of Eden and sent them to work the ground, the same dirt out of which they'd been made. He threw them out of the garden and stationed angel-cherubim and a revolving sword of fire east of it, guarding the path to the Tree-of-Life." -MSG
The way back into the Tree of Life must be through the flaming sword of the Lord. The natural man can only return with the loss of all he is.
thats right..the way back is thru the Fire !
Josephus Book 1 Chapt 2 part 69,70
Re; children of Seth;
They inhabited the country without dissension and in a happy condition without any misfortunes falling upon them till they died.
They were also the inventors of that peculiar wisdom which is concerned with heavenly bodies and their order.
They made two pillars of stone that their inventions might not be lost before they were sufficiently know about.
This was based upon Adam's prediction that the world was to be destroyed at one time by water and another time by fire.
Peter know this info in his quote at about end times;
2 Peter 3;5-7 .... heavens that have been stored, with fire being kept until the day of judgment."
The tree of life seems to be protected till that judgment has been carried out.
This was known by Adam, so must be a long-term project.
Another reason for the basis of all being saved, just some slightly before the rest- the first fruit.