One place where Tolkien makes explicit the metaphysical foundation of myth and fairy-story is his unfinished and little-known time-travel fantasy, The Notion Club Papers, in which an allusion is made to a broadly Aristotelian and hierarchical understanding of reality and hence of the different sciences responsible for studying that reality. When one character asks what is the source or soil of “ancient accounts, legends, myths, about the far Past, about the origins of kings, laws, and the fundamental crafts” if these accounts are to be something more than “wholly inventions” or “mere fiction,” another character gives the following, sober reply: “In Being, I think I should say… and in human Being; and coming down the scale, in the springs of History and in the designs of Geography—I mean, well, in the pattern of our world as it uniquely is, and of the events in it as seen from a distance” (Sauron Defeated 227). Again, mythology has its roots in the fertile soil of metaphysics, in a certain intuition of the being of things, and the same certainly holds true of Tolkien’s own mythology. As Tolkien scholar Verlyn Flieger has observed, from one vantage point the whole of Tolkien’s Silmarillion represents an “exploration of the implications and ramifications of the one word Eä,” the Elvish word meaning either the indicative “It is” or the imperative “Let it be,” the word Ilúvatar the Creator speaks when he at last brings the physical world into being. To the question, then, as to the relevance of metaphysics to Tolkien’s mythology, we may say that mythology is concerned with reality, and the question of reality for Tolkien is in its turn a question of being, of what exists and how it exists.
 Tolkien alludes to this same hierarchy or “scale” of being and its “patterns” of being in a letter to Camilla Unwin, the daughter of his publisher Rayner, answering Camilla’s question as to the purpose of life: “As for ‘other things’ their value resides in themselves: they ARE, they would exist even if we did not… If we go up the scale of being to ‘other living things’, such as, say, some small plant, it presents shape and organization: a ‘pattern’ recognizable (with variation) in its kin and offspring… And since recognizable ‘pattern’ suggests design, [human curiosity] may proceed to WHY? But WHY in this sense, implying reasons and motives, can only refer to a MIND” (L 399).
 Flieger, Splintered Light: Language and Logos in Tolkien’s World, 59.