Orcs are depicted as wholly evil, meaning that they could be slaughtered without regret. All the same, Orcs are human-like in being able to speak, and in having a similar concept of good and evil, a moral sense of fairness, even if they are not able to apply their morals to themselves. This presented Tolkien, a devout Roman Catholic, with a problem: since "evil cannot make, only mock", the at least somewhat sentient and morally-aware Orcs could not have been created by evil as a genuinely new and separate species; but the alternative, that they were corrupted from one of Middle-earth's free peoples, such as Elves, which would imply that they were fully sentient and had immortal souls, was equally unpalatable to him. Tolkien realized that some of the decisions he had made in his 1937 children's book The Hobbit, showing his goblins (orcs) as even slightly civilised, and giving his animals the power of speech, clearly implied sentience; this conflicted with the more measured theology behind his Legendarium.
