Ibnale was one of a dozen people in San Francisco who had been given $100 by a startup charity that is trying to get strangers to start doing nice things for other strangers. It’s a novel concept. Most folks, it turns out, aren’t prepared for it. “What’s the catch?” a man asked.

No catch, replied Ibnale. Take an umbrella. You’re getting wet.

“No, thanks,” the man answered, and kept walking through the rain. Ibnale began keeping count. He asked 27 wet people if they would like to have an umbrella. Seventeen of them said no.