Among the remarkable facts about Ahmed Chalabi was that after turning Iraq and America upside down and unleashing all the gods and devils of war, he died of natural causes in Baghdad this week. Few people have changed the course of the last few decades more, through the force of personality, than did Chalabi. Historians will argue the causes and consequences of the Iraq War, but my own guess is that if it hadn’t been for Chalabi, Saddam Hussein or one of his odious sons or henchmen would probably be ruling Iraq today.

Chalabi tirelessly lobbied to convince an America yearning for revenge after the Sept. 11, 2001, attacks to destroy his nemesis and Iran’s, his most steadfast patron. Iraqis must judge if this outcome was better for their country, but it certainly has proved worse for America.

Philosophers have debated for centuries what truly drives history. Is it great men and women and their world-historical ideas, as Georg Wilhelm Friedrich Hegel contended? Or is there a deeper force embedded in technology and economics [the “means of production,” as Karl Marx had it] that determines the story? Does God, however named, have a plan?

Chalabi led me to believe that it was individuals who made the difference. There was nothing inevitable about America’s invasion of Iraq and the catastrophic consequences that have flowed from the decision. Like most big things in life, this happened at the margins.

If Chalabi hadn’t lectured regularly at Professor Fouad Ajami’s class at the Johns Hopkins School of Advanced International Studies in the 1990s; if Paul Wolfowitz, later the deputy defense secretary, hadn’t been dean of that school then; if Wolfowitz and Vice President Dick Cheney hadn’t been enamored of Chalabi’s call to strike at the heart of Arab power by toppling Saddam; if Cheney hadn’t disdained the CIA, which tried to warn policymakers that Chalabi was unreliable … None of it was foreordained.

Chalabi was truly an operator – banker, politician, connoisseur, dirty-tricks coordinator and spy all thrown into one. I first met him in 1991 when he was helping international detective Jules Kroll recover Kuwaiti assets stolen by Iraq during its 1990 invasion. I wrote a novel, “The Bank of Fear,” based partly on that research. Chalabi could be uncommonly generous with his time and brilliance, but he had complicated personal agendas too, which were sometimes well-disguised.

During that time, I met Iyad Allawi, Chalabi’s great rival and eventually Iraq’s deputy prime minister. Over subsequent years, Chalabi grew distant, and by the time of his celebrity in the run-up to the Iraq War, we were barely speaking. My own mistakes in supporting the Iraq invasion, summarized in a 2013 column, cannot be explained by Chalabi or his weapons of mass destruction propaganda.

Chalabi, like his Iranian friends, played a long game in Iraq. When I called on him in Baghdad in April 2003, after the U.S. military had accomplished his dream of toppling Saddam, one of his aides barred the door, screaming, “Allawi lover.”

Chalabi emerged, his genial round face peering out from behind the door: “Now, now. We know David,” he said soothingly, taking me by the hand and leading me into his compound. I watched over the next several hours as he insisted that he was the Pentagon’s man in Baghdad, and that other Iraqis seeking U.S. support were out of luck.

The CIA got many things wrong about Iraq, but it had Chalabi right early on. The agency judged him as unreliable – and, more important, a man who had deep links with the revolutionary regime in Iran.

It’s one of the bizarre paradoxes of history that Chalabi was embraced by the pro-Israel neoconservative elite even as he was in contact with an Iran that sought Israel’s destruction. How did that happen? A whole library full of historians probably couldn’t explain it. It wasn’t a conspiracy. It was a mistake.

Chalabi did one thing that was surprising, given his cosmopolitan ways. He stayed on in Iraq, dickering with various factions for a slice of power, hoping always that he would emerge as a compromise candidate for prime minister. He had the quality so lacking in U.S. policy – persistence.

A two-word lesson from this extraordinary life: Be careful. History doesn’t have a “right side” or an ascending path toward the light. Passionate, world-changing people are sometimes liars, too. Americans need to know more than we do about the Middle East, before we wander into the web of a man as clever and supple as Chalabi.