I happened, the day after the Paris attacks, to pick up an old copy of The New Yorker and find James Wood’s remarkable review of the works of Primo Levi. “Evil is not the absence of the good, as theology and philosophy sometimes maintained," Wood writes of Levi’s Auschwitz memoir, If This is a Man. "It is the invention of the bad." Levi's "clarity is ontological and moral: these things happened, a victim witnessed them, and they must never be erased or forgotten.” Primo Levi never became 17451, the identity tattooed on him at Auschwitz. The insistence on remembering, no matter how horrific the memory; the assertion of one small human voice in response to unspeakable evil; the affirmation of the significance of each one of us – this, for me, is the legacy of the holocaust. And it is this that ISIS is intent on obliterating. Look at its short and ghastly history filled with: the destruction of antiquities and cultural icons; the extermination of the Yazidis and other peoples; the enslavement and rape of women; the mass executions in Tikrit, the bombings in Beirut, the killing spree in Paris. Each of these acts is intentionally indiscriminate, aimed not just at physical murder but at eradicating memory, destroying cultural identity, denying our common humanity.

We must not become complicit, either in demands for indiscriminate retaliation in which innocents are killed or in retreating from the world. “The business of living,” wrote Levi, “is the best defense against death, even in the camps.”

Next time we will return to the Climate and Energy series.