The quote comes from the last BBC radio broadcast in the series “Beyond Personality: The New Men” by C.S. Lewis March 21, 1944.
“In the same way, people who are still acting from their old natural selves won’t do much real permanent good to other people. Let me explain that. History isn’t just the story of bad people doing bad things. It’s quite as much a story of people trying to do good things. But somehow, something goes wrong. Take the common expression: “cold as charity.” How’d we come to say that? From experience. We’ve learned how unsympathetic and patronizing and conceited charitable people often are. And yet hundreds and thousands of them started out really anxious to do good, and when they’d done it, somehow it just wasn’t as good as it ought to have been.
The old story: What you are comes out in what you do. A crabapple tree can’t produce eating apples. As long as the old self is there its taint will be over all we do. We try to be religious and become Pharisees. We try to be kind and become patronizing. Social service ends in red tape of officialdom. Unselfishness becomes a form of showing off.
I don’t mean of course that we’re to stop trying to be good. We’ve got to do the best we can. If the soul’s just fool enough to go into battle with a dirty rifle he mustn’t run away. But I do mean that the real cure lies far deeper.”
The last episode is the only surviving recording of his broadcasts, it can be found here: http://www.lewissociety.org/audios.php Or in these two Youtube videos: (https://www.youtube.com/watch?v=JHxs3gdtV8A)