C. S. Lewis is Opaque

So, yesterday I spent hours looking through the third volume of CSL's COLLECTER ESSAYS. And, as has often proved the case,  I didn't find what I was looking for but came across a number of interesting things in the search. For example, I'm not quite sure how to take the following passage from a 1959 letter to the great Arthurian scholar Eugene Vinaver.  (III.1083-1084)

Have you read Tolkien's lecture on Fairy Stories in the volume Essays presented to Charles Williams?  Part of my case against the Celticists wd. be his mixim that 'motifs are a product of analysis' -- not bricks out of which stories are put together but entia rationis ['mental fiction'] into which we analyse them -- rather like the metrical feet or grammatical conjunctions and declensions.

I thought I knew ON FAIRY STORIES pretty well, but this 'maxim' doesn't ring a bell. Could this be an example of what JRRT called 'Lewisification'?**

--John R

--current viewing: RINGS OF POWER

*Hooper's note explains that by Celticist Lewis meant figures like Loomis who explained everything in Arthurian legend as derived from Celtic soures.

**For Tolkien's description of being 'Lewisified', see  LETTERS p.89.