Notwithstanding Tolkien’s and Thomas’s agreement where the doctrine of creation proper is concerned, on the subject of the creaturely power of mere making, particularly of angelic making, it has to be said that Tolkien departs boldly from the more conservative path tread by his great theological forbear. Whereas Tolkien in his fiction accords phenomenally vast sub-creative powers to the Valar, attributing to them the formation of such important and complex structures as the world’s geological formations, plant, and animal life, Thomas expressly denies, for example, that even the substantial forms of corporeal bodies are or can be communicated by angels (ST 1.65.4). Here, at least, Tolkien’s inspiration would indeed seem to have been more directly pre-Thomistic.
Although Eru is the one who first brings the world into being, the world he creates is, for the most part, entirely unformed, consisting of “wastes unmeasured and unexplored” (S 20). The primary responsibility Ilúvatar gives to the Valar, accordingly, is that they should labor to make the world inhabitable for the coming of the Children of Ilúvatar, whom Eru will create himself, and all in fulfillment of what the Valar had seen in the Vision. Thus, at the conclusion of the Ainulindalë it is said that the Valar delved valleys, carved mountains, and hollowed seas, indicating that much of the initial geography of the world is to be attributed to their handiwork. Even more remarkable is that the Valar are also made responsible for the introduction of plant and animal life in the world. It is Yavanna, for example, the spouse of Aulë, who
planted at last the seeds that she had long devised… and there arose a multitude of growing things great and small, mosses and grasses and great ferns, and trees whose tops were crowned with cloud as they were living mountains, but whose feet were wrapped in a green twilight. And beasts came forth and dwelt in the grassy plains, or in the rivers and the lakes, or walked in the shadows of the woods. As yet no flower had bloomed nor any bird had sung, for these things waited still their time in the bosom of Yavanna… (S 35)
The most renowned of Yavanna’s works are the Two Trees of Valinor, Telperion and Laurelin, from whose golden fruit and silver leaf the Valar later fashion the sun and the moon themselves. As for the rest of the celestial bodies, many of the stars are also accounted as having been “wrought” by Varda, the “Lady of the Stars” and spouse of Manwë (S 26, 39).
It is the story of Aulë’s foolish and futile attempt at making the dwarves, however, that best illustrates both the tremendous magnitude of and the intrinsic limits imposed upon the Valar’s sub-creative power. The Silmarillion tells how Aulë, out of an otherwise noble desire for there to be “things other” than himself who might enjoy the beauty of the world, yet in his impatience for the coming of the Children of Ilúvatar, made the dwarves out of earth and stone. Rebuking Aulë afterwards for his presumption, Ilúvatar inquired of him:
Why hast thou done this? Why dost thou attempt a thing which thou knowest is beyond thy power and thy authority? For thou hast from me as a gift thy own being only, and no more; and therefore the creatures of thy hand and mind can live only by that being, moving when thou thinkest to move them, and if thy thought be elsewhere, standing idle. Is that thy desire? (S 43)
Although Eru alone can give being, Aulë is nevertheless able to turn the earth and stone which Eru had created into, if not free, rational beings, as Aulë had intended, then at least into living yet witless organisms. It is only as a supernatural gift from Ilúvatar, graciously bestowed in response to Aulë’s humble repentance, that the dwarves come to have “a life of their own, and speak with their own voices” (S 44). Thus, while in his letter to Hastings Tolkien wanted to leave open the possibility that the Orcs could have been “made” by the dark powers, he also denies the “making of souls or spirits, things of an equal order if not an equal power to the Valar, as a possible ‘delegation’…” (L 195). Related to Aulë’s production of the dwarvish bodies is the idea, later entertained by Tolkien, that the spirits of deceased Elves, instead of becoming reincarnate through a second, physical rebirth, might have their new bodies prepared for them by the Valar (MR 339, 362, and 364).
 The sun and the moon are actually fashioned long after Ilúvatar’s creation of the Elves, a sequence of events Tolkien later came to regret. As he put it in one commentary, “you can make up stories of that kind when you live among people who have the same general background of imagination, when the Sun ‘really’ rises in the East and goes down in the West, etc. When however (no matter how little most people know or think about astronomy) it is the general belief that we live upon a ‘spherical’ island in ‘Space’ you cannot do this any more” (MR 370).
 Thus, as Tolkien himself concludes in his letter to Hastings, the question of whether the Orcs were “made” or not is a “different question” from whether or not the Orcs had “souls” or “spirits” (L 195).