Last year, a friend placed a slim book on my desk. The cover was simple. The title: "The Art of Gathering" by Priya Parker.

"I know you host gatherings often," he said. "Read this. It will change the way you invite people."

I read it in two days. But one sentence remains underlined to this day:

"Every gathering must begin with a clear decision: what are we gathering for? If you can't answer that, don't hold the gathering."