The Straight Road

[Nogrod]

Adding to the the wealthy examples by Morthoron, I'd say that in the simple plane it would be easy to just state there is a one-way traffic-line there. Whether someone from the Middle-Earth was approaching, who was not permitted the seas would just arise and prevent them from getting anywhere - and the same would go for any of the "blessed" who would try to to reach the M-E as there would be no admission without a special purpose (like Gandalf geting back wherever it was he was while "dead").

Originally Posted by Lal

Afterwards, the earth was curved and if you set sail from Middle-earth's western shores you'd just eventually come back to the eastern ones (presumably a bit thirsty and as bonkers as the Ancient Mariner by then).

That kind of brings to my mind the then (and now) hot debates over quantum physics, the possibilities of wormholes, the parallel universes, the curved universe with relation to the Einstein's speculations which Tolkien must have known...

The idea surely is an interesting one - and it has this "down to earth" -explanation available even if the physical science professionals wouldn't allow it - where the world actually goes around itself and gives you the the round globe; but on another plane the laws would be different and you only have access to them through those wormholes / parallel universes etc... And linking them with old myths about "moving to a different plane" would fit the mythologial structures of the worlds of every conceivable nation or tribe living up north about 1000 AD or before that...

Kind of a stuff Robert Holdstock used later?