" Oui. There’s always a reason, even if reason doesn’t figure into it. It almost always starts with some emotion. A hurt feeling. A slight. An insult, a betrayal. It digs in like a hook, and festers. Dragging that person toward the cliff. It could take years, and for some it never goes that far. It becomes a low-level hum of anger all their lives. "

― Louise Penny , The Madness of Crowds (Chief Inspector Armand Gamache, #17)