At some point after he became chief surgeon in Napoleon’s army, Dominique Jean Larrey started walking across blood-soaked battlefields to pick out those among the wounded who could still be saved, usually by instant amputation of limbs. In time, he developed a system of sorting and separating — trier in French — the casualties. Ignoring rank and nationality, he considered only those who had the greatest chance of surviving. His method became known as triage.
In worst-case scenarios, triage is nowadays accepted almost universally as necessary and justified. And yet, the idea still rests on an act of cruelty — cruel both to a victim and to the doctor having to make the decision. It often necessitates allowing one human being to die in order to ration the care that might let another live.