Learning is a result of listening, which in turn leads to even better listening and attentiveness to the other person. In other words, to learn from the child, we must have empathy, and empathy grows as we learn.
Contempt is the weapon of the weak and a defense against one's own despised and unwanted feelings.
If it's very painful for you to criticize your friends - you're safe in doing it. But if you take the slightest pleasure in it, that's the time to hold your tongue.
It is very difficult for people to believe the simple fact that every persecutor was once a victim. Yet it should be very obvious that someone who was allowed to feel free and strong from childhood does not have the need to humiliate another person.