You probably want to be safe much more than you want to help the man who is drowning: but the Moral Law tells you to help him all the same. And surely it often tells us to try to make the right impulse stronger than it naturally is? I mean, we often feel it our duty to stimulate the herd instinct, by waking up our imaginations and arousing our pity and so on, so as to get up enough steam for doing the right thing. But clearly we are not acting from instinct when we set about making an instinct stronger than it is. The thing that says to you, ‘Your herd instinct is asleep. Wake it up,’ cannot itself be the herd instinct. The thing that tells you which note on the piano needs to be played louder cannot itself be that note.
C.S. Lewis, Mere Christianity (1952, this edition: 2001) 10.