Between the third and fifth centuries of the Christian era the major world religions ceased to sacrifice animals to appease their gods. For reasons that remain unclear, a practice that had been central to devotional behaviour for thousands of years came to appear grotesque. Joseph Farrell observes that the practice of duelling is now similarly ‘uniformly judged as outlandish and incomprehensible’, its ‘canons and creeds … as beyond recall as the beliefs of the ancient Egyptians’. For five hundred years men of a certain rank settled disputes with sword or pistol in accordance with an elaborate etiquette involving a formal challenge, the appointment of seconds and the negotiation of a time and place for a contest governed by strict rules. The angry brawl was drained of passion, made mindful and even elegant. A doctor was always on hand, but deaths were common. Then, in the second half of the 19th century, the practice declined and disappeared. It’s ‘the sheer incomprehensibility’ of all this that prompted Farrell to write his book. If the duellists were Christian gentlemen, he asks, why did they not see the duel’s incompatibility with basic morality? Why didn’t the state intervene more effectively to prevent individuals from taking the law into their own hands? Why were so many men willing to risk their lives over disputes that often seem trivial?