When I was younger, I called Vietnam – the conflict of my youth and my generation – “the war that never ends.”

Now Iraq is threatening to become that war as we are drawn back into its political and humanitarian crises. It was, of course, the wrong war, which President Barack Obama pointed out when he was a senator, the war for al-Qaeda being the province of Afghanistan. But we went anyway, little understanding the culture (echoes of Vietnam) or the lesson of Alexander the Great – that to conquer you must immerse yourself in a place and be prepared to risk being seduced, being conquered, by the place itself.

Alexander – the Greco-Macedonian conqueror of the Persian Empire – never left Iraq, dying in Babylon a month short of his 33rd birthday. We left, but in leaving, stayed.

Iraq figures into one of the four story arcs that make up my new novel, “Water Music,” about the tennis prodigy Alí Iskandar – a favorite character of my readers...