The curse of Morgoth in CoH.

[William Cloud Hicklin]

Do you have quotes? I don't recall this from MR (then again, it's been about a year since I read it). The reason, as far as I could gather, for Morgoth's decrease in power was due to his putting his power into his servants, not the earth itself

"To gain domination over Arda, Morgoth had let most of his being pass into the physical constituents of the Earth- hance all things that were born on Earth and lived on or by it, beasts or plants or incarnate spirits, were liable to be 'stained'...Melkor 'incarnated' himself (as Morgoth) permanently. He did this so as to control the hroa, the flesh or physical metter, of Arda. He attempted to identify himself with it...Thus, outside the Blessed Realm, all 'matter' was likely to have a 'Melkor ingredient', and those who had bodies, nourished by the hroa of Arda, had as it were a tendency, small or great, towards Melkor: they were none of them wholly free of him in their incarnate form, and their bodies had an effect upon their spirits.....The whole of Middle-earth was Morgoth's Ring."

EDIT: X-posted with Raynor