I met Arnold, 95, at a New York City senior center. A victim of Nazi persecution, Arnold fled Germany to the United States and made a good life for his family. He believes that curiousity and tolerance are the keys to lifelong happiness. He’s a funny guy, so he began with a joke.

You ask about life lessons? I will tell you a story. A father talks to his son, and he says to his son, I want to talk to you about sex. And the son says, “Dad, what do you want to know?”

There’s your answer. We have to learn from the young and always stay curious. I had such convictions that I changed completely. Circumstances taught me that what I believed wasn’t so. One of my advantages is that I am willing to recognize change. In life, we are confronted with constant change, and you can’t be dogmatic. You see what happens with nations, what happens with people when they are dogmatic. You have to be open, be involved in new things.