Not Mine...Lewis'

"You can be good for the mere sake of goodness: you cannot be bad for the mere sake of badness. You can do a kind action when you are not feeling kind and when it gives you no pleasure; simply because kindness is right; but no one ever did a cruel action simply because cruelty is wrong-only because cruelty was pleasant or useful to him. In other words badness cannot succeed even in being bad in the same way in which goodness is good. Goodness is, so to speak, itself: badness is only spoiled goodness. And there must be something good first before it can be spoiled. We call sadism a sexual perversion; but you must first have the idea of a normal sexuality before you can talk of its being perverted; and you can see which is the perversion, because you can explain the perverted from the normal, and cannot explain the normal from the perverted. It follows that this Bad Power, who is supposed to be on an equal footing with the Good Power loves goodness, is a mere bogy. In order to be bad, he must have good things to want and then to pursue in the wrong way: he must have impulses which were originally good in order to be able to pervert them. But, if he is bad he cannot supply himself either with good things to desire or with good impulses to pervert. He must be getting both from the Good Power. And if so, then he is not independent. He is part of the Good Powers world: he was made either by the Good Power or by some power above them both.

Put it more simply still. To be bad, he must exist and have intelligence and will. But, existence, intelligence and will are in themselves good. Therefore, he must be getting them from Good Power: even to be bad he must borrow or steal from his opponent. And do you now see why Christianity has always said that the devil is a fallen angel? That is not a mere story for the children. It is a real recognition of the fat that evil is a parasite, not an original thing. The powers which enable evil to carry on are powers given it by goodness."


lewis 

excerpt taken from Mere Christianity by C.S. Lewis in his chapter entitled "The Invasion" (P.44,45)