My life in the decades since, both in and out of government, has been enriched by the survivors of other extraordinary times. During my time as secretary of state, I met a 6-year-old boy in Uganda whose mother had been killed in a massacre. He had pulled himself out from under her body and walked several miles, carrying his little sister on his back, to a camp run by a religious organization. In Sierra Leone, I held a 3-year-old girl who had lost her arm to a bullet; she was later adopted and lived on the same street I do in Washington.

In Bosnia, I grasped hands with women whose husbands and sons had been murdered and dumped in a mass grave near the village of Srebrenica. In Thailand, I met teenage girls who had been rescued from sex traffickers; they braided one another’s hair while telling me of their determination to live fearlessly despite scarred minds. At Georgetown University, back in Washington, I taught alongside a professor, Jan Karski, who had escaped from wartime Poland carrying to Britain and America some of the earliest eyewitness accounts of the transport of Jews to killing centers ordered by Hitler.

During my tenure in the State Department, I worked closely with Vaclav Havel, leader of my native Czech Republic, and with South Africa’s Nelson Mandela; both had spent years as political prisoners. I also visited American soldiers, aviators, diplomats, aid workers and Peace Corps volunteers deployed to regions where each day brought intense suffering and renewed conflict.

As president, Bill Clinton talked often about “the quiet miracle of a normal life.” But what we customarily think is “normal” is neither as common as supposed, nor as inevitable. A generally contented society is a rarity that humans must do our best to establish and sustain.

Flawed as we are, we have built great civilizations, learned to coexist and — with catastrophic exceptions — live in peace. However, such accomplishments do not happen without obstacles. To be human is to be tested over and over, and we usually need abundant help from others.