Tolkien’s passing remark that his realization of this profound truth concerning angelic causality (see yesterday’s post) produced in him a “great sense of joy,” is itself not without significance, as it links his dialectic of divine presence to another central theme in his writing. In another earlier post I argued that Eru’s temporary absence from the narrative is what later makes possible an even more violent or striking manifestation of his ever-abiding presence. This divine “intrusion” into the story, undertaken for a specifically redemptive or salvific purpose, is the metaphysical and theological framework behind Tolkien’s well-known concept of eucatastrophe (literally “good catastrophe”), a neologism Tolkien coined in his essay “On Fairy-Stories” to describe the literary device of the “happy ending,” the “sudden joyous ‘turn’” that is the “mark of a good fairy-story” (TR 86-7). Tolkien describes the existential experience of eucatastrophe in this way: “however wild its events, however fantastic or terrible the adventures… when the ‘turn’ comes, [there is] a catch of the breath, a beat and lifting of the heart…” (TR 86). More than a mere literary device, however, Tolkien believes eucatastrophe, along with the seemingly universal hold it wields over the human imagination, points to a profound metaphysical truth, namely the possibility and even reality of the “sudden miraculous grace: never to be counted on to recur.” As Tolkien described the same phenomenon in a letter to his son Christopher, eucatastrophe is “that sudden glimpse of the truth behind the apparent Anankê [Greek for necessity, constraint, or what Tolkien refers to immediately before as “nature chained in material cause and effect, the chain of death”] of our world, but a glimpse that is actually a ray of light through the very chinks of the universe about us” (L 100-1). The identity of this “ray of light” shining “through the very chinks of the universe” Tolkien indicates further in another letter defining the role of divine presence and providence in The Lord of the Rings generally:
I have purposely kept all allusions to the highest matters down to mere hints, perceptible only by the most attentive, or kept them under unexplained symbolic forms. So God and the “angelic” gods, the Lords or Powers of the West, only peep through in such places as Gandalf’s conversation with Frodo: “behind that there was something else at work, beyond any design of the Ring-maker’s” or in Faramir’s Númenórean grace at dinner. (L 201)
Tolkien expresses the same principle in his account of the eucatastrophe that occurs at the end of The Lord of the Rings when Frodo fails to destroy the Ring of his own free will. Of the Creator’s personal involvement at that moment Tolkien writes: “Few others, possibly no others of his time, would have got so far [as Frodo did]. The Other Power then took over: the Writer of the Story (by which I do not mean myself), ‘that one ever-present Person who is never absent and never named’ (as one critic has said)” (253, emphasis added). For Tolkien, in summary, fairy-stories represent one of the highest of human art forms; one of the essential devices of “a good fairy-story” is the eucatastrophic turn; and at the heart of Tolkien’s understanding of the eucatastrophic turn is his Thomistic recognition of an eminently personal, involved God who nonetheless deliberately hides himself under the veil of natural, secondary, and even angelic causality, so that he might then tear aside the veil of his own devising—like a child in a cosmic game of peek-a-boo—and show himself present, strong, and faithful to those who know and serve him.
 Here we might contrast Tolkien’s own self-understanding with Catherine Madsen’s deistic, secularized reading of the eucatastrophes of Tolkien’s fiction: “Tolkien never forces cosmology into these moments of attention… For that moment, the unexpected presence of beauty in the midst of desolation is enough to assure that beauty will endure forever—because of the otherness of the other, because of its very distance, perhaps (could one see it as beauty) because of the very distance of God.” Ibid., 44. Christopher Garbowski, however, I think gives a more accurate account of the ultimately divine pattern behind Tolkien’s concept of eucatastrophe: “the concept becomes closely associated with his concept of ‘sub-creation,’ which is introduced in the same essay [“On Fairy-Stories”]. In subcreation, by telling stories or inventing worlds the artist effectively imitates the ‘Primary Creator.’ … Consequently, since the Primary Creator ultimately intends humans to be happy, the artist that evokes eucatastrophe is creating in consonance with God. Moreover, if the deepest sense of story is consonant with revelation, the concept approaches natural theology with a Christian humanist perspective.” Christopher Garbowski, “Eucatastrophe,” in Drout, ed., J.R.R.T. Encyclopedia, 176.