The brilliance of the plan was that the wergild (often the offender’s entire assets, together with additional money rounded up from his family) went to the king instead of to the family of the victim. Justice was administered by roving courts that would periodically visit a locale and hear the accumulated cases. To ensure that all homicides were presented to the courts, each death was investigated by a local agent of the crown: the coroner. Once Leviathan was in charge, the rules of the game changed. A man’s ticket to fortune was no longer being the baddest knight in the area but making a pilgrimage to the king’s court and currying favor with him and his entourage. The court, basically a government bureaucracy, had no use for hotheads and loose cannons, but sought responsible custodians to run its provinces. The nobles had to change their marketing. They had to cultivate their manners, so as not to offend the king’s minions, and their empathy, to understand what they wanted. The manners appropriate for the court came to be called “courtly” manners or “courtesy.” The etiquette guides, with their advice on where to place one’s nasal mucus, originated as manuals for how to behave in the king’s court. Elias traces the centuries-long sequence in which courtesy percolated down from aristocrats dealing with the court to the elite bourgeoisie dealing with the aristocrats, and from them to the rest of the middle class. He summed up his theory, which linked the centralization of state power to a psychological change in the populace, with a slogan: Warriors to courtiers.

The second exogenous change during the later Middle Ages was an economic revolution. The economic base of the feudal system was land and the peasants who worked it. As real estate agents like to say, land is the one thing they can’t make more of. In an economy based on land, if someone wants to improve his standard of living, or for that matter maintain it during a Malthusian population expansion, his primary option is to conquer the neighboring lot. In the language of game theory, competition for land is zero- sum: one player’s gain is another player’s loss.