[MHGinTN]

It is turtles all the way down only so long as the last turtle, the one on the bottom, is metaphysical.

[MineralMan]

"It is turtles all the way down only so long as the last turtle, the one on the bottom, is metaphysical."

There is no last turtle. Even metaphysical turtles need a place to stand. Once you move into the metaphysical realm, it's just one metaphysical turtle standing on the back of the one below. There is no bottom turtle. It is turtles all the way down.