Brooks: The secrets of lasting friendships

In early 2020, just before the start of the pandemic, I met a woman who said she practiced “aggressive friendship.” It takes a lot of her time, but she’s the person who regularly invites friends over to her house, who organizes events and outings with her friends. What a fantastic way to live. I thought of her while reading Robin Dunbar’s recent book, “Friends.” If the author’s name means something to you, it’s probably because of Mr. Dunbar’s number.