"The Shape Of The Narrative In The Lord Of The Rings"
is an analytical essay by Diana Wynne Jones
When Diana Wynne Jones was an undergraduate she attended some lectures that Tolkien gave. Here she uses quotes and examples to explain Tolkien's mastery of the narrative, which is more than just the plot and how he wove his stories
It is in the short story collection Everard's Ride and J R R Tolkien: This Far Land.