But the problem with talking about the origin of Orcs is that J.R.R. Tolkien kept changing his mind about it. Adar and Galadriel’s conversation gets to the heart of why he struggled so much, and it comes down to his Christian faith and the theological aspects of his mythology. The Christian theological side of Tolkien’s work is far less well known than that of his friend C.S. Lewis, who was a famous lay theologian and whose use of the character of Aslan the lion as a Christ figure has annoyed many critics and writers over the years. Tolkien may have been one of them; he and Lewis were different Christian denominations – Lewis was Protestant and Tolkien was Roman Catholic – and Tolkien didn’t like allegory very much.
But Tolkien’s works are also Christian works if you dig deep enough, and this where Galadriel and Adar’s argument about Orcs comes in. The issue Tolkien had with Orcs was that he had created a whole race of beings that was basically evil. Orcs are nearly always seen serving Morgoth, or Sauron, or Saruman after his turn to the Dark Side. When they’re not serving some kind of Dark Lord, they’re hanging around the Misty Mountains attacking passing Dwarves (and one Hobbit).
Having made up this completely evil species of beings, Tolkien had a problem. Life in his lore was created by Ilúvatar, who is basically God. Ilúvatar is the “One,” the “Master of the Secret Fire” that Adar mentions to Galadriel. When Gandalf tells the Balrog of Moria that he is a “servant of the Secret Fire,” he’s referring to Ilúvatar and the power of creation that comes from this fire.
Since Ilúvatar is inspired by the Christian concept of God, he can’t directly create anything totally evil. So Tolkien’s initial idea was that the Orcs were created by Morgoth. Morgoth is one of the Valar, the Children of Ilúvatar, who are a bit like Christian saints, Christian angels, and pagan gods and goddesses, all rolled into one. Morgoth is a bit like Lucifer, a Valar who defied Ilúvatar and turned to the dark side, just as Lucifer/Satan is a fallen angel. In early versions, eventually published after Tolkien’s death as The Book of Lost Tales, Morgoth created the Orcs as a “mockery” of the Elves, to mock Ilúvatar.
But then Tolkien decided that wouldn’t work either, because only Ilúvatar can create life. This is where we get to the version of the origin story that appears in The Silmarillion, where Tolkien suggests that Orcs are Elves who were “corrupted and enslaved” in the “pits of Utumno” and in this way Morgoth was able to “breed the hideous race of Orcs.” Utumno, one of Morgoth’s fortresses, was also known as “Udûn,” which is the title of episode 6, and this seems to be the version the show is going with.
Christopher Tolkien explained in his History of Middle-earth that Tolkien had made a note on this particular bit of lore in the margins, saying “Alter this. Orcs are not Elvish.” Presumably Tolkien had decided that his wonderful, beautiful, noble Elves couldn’t possibly be “corrupted” into evil Orcs. The text of The Silmarillion also says only that some of the Elves thought that this was the origin of Orcs, which gives some room for interpretation.