With a powerful blow, the Secretary-General of the United Nations, António Guterres, made the World Peace Bell ring. The sound quickly faded away. At the traditional ceremony to mark World Peace Day, Guterres made an appeal to the 193 UN member states, which sounded formulaic: “We have the opportunity to change something, in short, we must build a culture of peace,” Guterres said last week at the UN headquarters in New York.