A bit long but, I think, well worth reading to see what contributed to Tolkien's vision of both good and evil in the LOTR
https://www.weeklystandard.com/joseph-l ... somme-1916
Some Backstory to LOTR
1"Eternity is an awful long time, especially towards the end."
"What you see and what you hear depends a great deal on where you are standing.
It also depends on what sort of person you are.” -- CSL