" What haunted people even, perhaps especially, on their deathbed? What chased them, tortured them and brought some of them to their knees? And [he] thought he had the answer. Regret. Regret for things said, things done, and things not done. Regret for the people they might have been. And failed to be. "

― Louise Penny , The Brutal Telling (Chief Inspector Armand Gamache, #5)