“Why was the human being created as an individual? To teach you that one who destroys a single human life is as though he has destroyed an entire world. And one who saves a single human life is as though he has saved an entire world.” —Mishnah, Sanhedrin 4:5. Simple arithmetic does not apply when dealing with human lives. Each individual equals an entire world. The Talmud provides a practical application: A caravan traveling on the road is accosted by strangers who tell them, “Give us one of you and we will kill...