The Twist by Roald Dahl
It’s not from my favourite book, but I think about this often; I think about this when I have doubts about my character and the path that I’m on, I think about this when I need the comfort it provides me, I think about it this when I look at someone’s face and I don’t understand why it brings me peace (or anxiety).
A person who has good thoughts cannot ever be ugly. You can have a wonky nose and a crooked mouth and a double chin and stick-out teeth, but if you have good thoughts they will shine out of your face like sunbeams and you will always look lovely.
I think that was the first time something like that ever got underneath my skin.