What did Tolkien really mean ....

[Fordim Hedgethistle]

OK -- being terribly reductive and probably simplistic here...but couldn't Tolkien simply have been acknowledging the difference between the creating-writer who pens a first draft and the editing-writer who takes that great shambles and renders it "finished" insofar as he makes sure that it "makes sense" (i.e. is internally coherent, presents a unified story and vision of its characters and action).

The creating-writer (in this model) simply goes with the story and gets it down. The editing-writer is one who shapes that material -- and given that Tolkien was Catholic and his work engages with moral issues it makes sense that this act of re-vision would be undertaken from that perspective.

Maybe the Professor was just being honest: "As I was revising the story I was conscious of the fact that I was a Catholic man who was reshaping it and rendering it coherent."