Tolkien’s metaphysics of evil, part 22
For Aquinas, then, the presence of evil in the world is necessary to make possible certain kinds of good, such as avenging justice. Some, however, have found such rational theorizing cold and unfeeling towards the cruel realities of human suffering in the world. Yet for Tolkien this truth was the source of deep personal comfort, as may be seen in the following, unflinching encouragement he offered his son Christopher while the latter was in South Africa training as a pilot during the Second World War:
I sometimes feel appalled at the thought of the sum total of human misery all over the world at the present moment: the millions parted, fretting, wasting in unprofitable days—quite apart from torture, pain, death, bereavement, injustice. If anguish were visible, almost the whole of this benighted planet would be enveloped in a dense dark vapour, shrouded from the amazed vision of the heavens! And the products of it all will be mainly evil—historically considered. But the historical version is, of course, not the only one. All things and deeds have a value in themselves, apart from their “causes” and “effects.” All we do know, and that to a large extent by direct experience, is that evil labours with vast powers and perpetual success—in vain: preparing always only the soil for unexpected good to sprout in. So it is in general, so it is in our own lives… (Letters 76)
Like St. Thomas, then, Tolkien too held to a kind of greater-good theodicy, though it was one that he affirmed in the face of seemingly overwhelming evidence to the contrary, namely the “vast powers and perpetual success” of evil which nevertheless, in the final analysis, will be seen as having labored “in vain.” So important is this promise that evil will indeed result in greater good that it is given expression in the Ainulindalë by none other than Ilúvatar himself, who, after bringing the Ainur’s Music to its climactic, triumphant resolution, declares:
‘Mighty are the Ainur, and mightiest among them is Melkor; but that he may know, and all the Ainur, that I am Ilúvatar, those things that ye have sung, I will show them forth, that ye may see what ye have done. And thou, Melkor, shalt see that no theme may be played that hath not its uttermost source in me, nor can any alter the music in my despite. For he that attempteth this shall prove but mine instrument in the devising of things more wonderful, which he himself hath not imagined… And thou, Melkor, wilt discover all the secret thoughts of thy mind, and will perceive that they are but as part of the whole and tributary to its glory.’ (S 17)
As Ilúvatar explains to Melkor, the ultimate meaning of his rebellion will prove to be entirely different from the one intended by him. Not only is Ilúvatar the only one who can create and therefore give being to the sub-creative designs of his creatures, but for this very reason he is also the one who determines the ultimate meaning and outcome of the sub-creative choices of his creatures, whether they be good or evil.  It is this peculiar power of turning evil inexorably to good, in short, that distinguishes Ilúvatar as the one and only true Creator, allowing Melkor and all the Ainur to “know” that he is Ilúvatar. In addition to Melkor’s rebellious music succeeding by Ilúvatar’s design in making the Music more beautiful, and similar to what we saw in St. Thomas, there is a respect in which the beauty achieved in the Music through Melkor’s evil could not have been realized in any other way. As it is described in the Ainulindalë, Ilúvatar’s musical response to Melkor’s discord was “deep and wide and beautiful, but slow and blended with an immeasurable sorrow, from which its beauty chiefly came.” It is this idea, moreover, of the necessity of sorrow for the possibility of a certain kind of joy that lies at the heart of Tolkien’s concept of eucatastrophe, “the joy of the happy ending” or “sudden joyous ‘turn’” which “does not deny the existence of dyscatastrophe, of sorrow and failure,” inasmuch as “the possibility of these is necessary to the joy of deliverance” (Tolkien Reader, 85-6).
To return to the Ainur’s Music, inasmuch as it contains within itself a preview of subsequent world history, we also find in Tolkien something of the Thomistic thesis that the eventual existence of evil in the world was not only a possibility, but in some sense an inevitability. “In this Myth,” as Tolkien explains in one letter,
the rebellion of created free-will precedes creation of the World (Eä); and Eä has in it, subcreatively introduced, evil, rebellions, discordant elements of its own nature already when the Let it Be was spoken. The Fall or corruption, therefore, of all things in it and all inhabitants of it, was a possibility if not inevitable” (Letters 286-7).
In holding that, given free will, the existence of evil was probable if not inevitable, Tolkien was in basic agreement with his good friend C.S. Lewis, who in his Problem of Pain, as Elizabeth Whittingham points out, argues that if God creates people with free will, suffering and evil will probably exist, but their existence does not contradict God’s existence” (“The Mythology of the “Ainulindalë: Tolkien’s Creation of Hope,” 218).
 See, for example, Hart’s critique in The Doors of the Sea (although I think Hart fails to see how Aquinas likewise falls under his indictment of such Leibnizian, greater-good theodicies).
 See also Morgoth’s Ring 383.
 Ilúvatar’s speech is referred to later on in The Silmarillion in the Valar Manwë’s response to the Elf-lord Fëanor’s declaration that the Noldor Elves would leave their refuge in Valinor and return to Middle-earth to wage war against Melkor: “But at that last word of Fëanor: that at the least the Noldor should do deeds to live in song for ever, [Manwë] raised his head, as one that hears a voice far off, and he said: ‘So shall it be! Dear-bought those songs shall be accounted, and yet shall be well-bought. For the price could be no other. Thus even as Eru spoke to us shall beauty not before conceived be brought into Eä, and evil yet be good to have been.’ But Mandos said: ‘And yet remain evil. To me shall Fëanor come soon’” (S 98). Robert Collins has also touched on the necessity of evil for the achievement of certain kinds of goods in Tolkien’s writings: “Tolkien has embedded not only an analog of the ‘progressive’ Hegelian dialectic, but also an aesthetic analog of the Christian paradox of the ‘fortunate fall.’ Unopposed, the forces of concord may not conceive the beauty of the snowflake. Untempted, unfallen, man may not achieve the glory of sainthood.” Collins, “’Ainulindalë‘: Tolkien’s Commitment to an Aesthetic Ontology,” 260.