Will of the Nazgul/Creating More Nazgul

[Pitchwife]

Just a few clarifying words from the mouth of the horse (Gandalf in LotR Book I, The Shadow of the Past):

'A mortal, Frodo, who keeps one of the Great Rings, does not die, but he does not grow or obtain more life, he merely continues, until at last every minute is weariness. And if he often uses the Ring to make himself invisible, he fades: he becomes in the end invisible permanently, and walks in the twilight under the eye of the dark power that rules the Rings. Yes, sooner or later [...] the dark power will devour him.'[emphasis mine, Pw.]

Much as I like Gordis' line of argumentation (especially the bit about the Rings turning a Man into an Elf-like state!), this doesn't sound as if the process of 'wraithifying' and enslavement to Sauron were entirely unrelated.