On The Fall
The doctrine of the Fall (both of man and of some “gods,” “eldils” or “angels”) is the only satisfactory explanation.
Evil begins, in a universe //where all was good, from free will,
which was permitted /because it makes possible [the greatest good of all].
[The corruption of the first sinner] consists /not in choosing some evil thing (there are no evil things for him to choose)
but in preferring a lesser good (himself) before a greater (God).
The Fall is, in fact, Pride.
The possibility of this wrong preference is inherent in the v. fact of having, or being, a self at all.
But though freedom is real it is not infinite.
Every choice reduces a little one’s freedom to choose the next time.
There therefore comes a time //when the creature is fully built, irrevocably attached either to God or to itself.
This irrevocableness is what we call Heaven or Hell.
[Every conscious agent] is finally committed /in the long run: i.e., it rises above freedom into willed,
but henceforth unalterable, union with God, or else sinks below freedom into the black fire of self-imprisonment.
That is why the universe (as even the physicists now admit) has a real history,
a fifth act with a finale //in which the good characters “live happily ever after” and the bad ones are cast out.
At least that is how I see it.
From The Collected Letters of C.S. Lewis, Volume II
Compiled in Words to Live By