But if McCain has proved less than the ideal messenger, he has achieved something larger: He is an ideal message. When the time comes, his whole life story will be recalled, but its essence can be distilled to a single choice.

Shot down over Hanoi in 1967, McCain was taken prisoner with three of his limbs broken, his shoulder crushed and a bayonet wound in his gut. But this was no ordinary prisoner. In the long history of the U.S. Navy, McCain was the first to be both son and grandson of full admirals, and his father was in command of all operations in Vietnam. When his captors learned this, they offered McCain his freedom. He had only to exercise his privilege, look after himself, and leave his fellow prisoners behind.

They tortured him nearly to death for refusing, bound his broken arms, beat his unhealed wounds. Decades later, I watched him limp into rallies on a leg that could never be properly repaired and raise his shattered and rebroken arms waist-high — their full extent. And I heard him ask his fellow Americans to trust, as he had trusted through more than five years of avoidable suffering, in duty, service and one another.