“Here’s where the whole populism and nationalism thing came from,” Steve Bannon told me. It was February, and he was sitting in his White House office in a chair pushed against the wall, with a dry-erase board opposite him listing all the promises that just-inaugurated President Trump was going to carry out (“drain the swamp,” etc.). But first, Bannon wanted to explain the ideas that drove Trump’s shocking upset, to put that victory into a broader context. With Bannon, everything is always about something much bigger.

Trump’s rise was, he said, transformative for America. But it was only one manifestation of a powerful global undercurrent. “That’s why,” he said, “you see a nationalist movement in Egypt, India, the Philippines, in South Korea, and now Abe in Japan. I’d say Putin and Xi in China are nationalists. Look at Le Pen in France, Orban in Hungary, and the nationalists in Poland.” Trump was, of course, the most consequential: “Look, I’ve been studying this for a while, and it’s amazing that Trump has been talking about these ideas for 25 years.”

By this point, Bannon’s term for his politics, and Trump’s—“nationalism”— was already in wide circulation in the political press. But the term’s meaning was (and remains) opaque and has never been fully explicated. While Trump’s embrace of “America first” nationalism was chiefly due to its resonance as a campaign slogan, Bannon’s attraction to it had a far deeper and more complicated lineage.

Bannon’s a political entrepreneur and a remarkable bloke.

From an early age, Bannon was influenced by his family’s distinctly traditionalist Catholicism and he tended to view current events against the broad sweep of history. In 1984, after Pope John Paul II permitted limited use of the Latin-only Tridentine Mass, which was banned by the Second Vatican Council, Bannon’s parents became Tridentine Catholics, and he eventually followed. Though hardly a moralizing social conservative, he objected bitterly to the secular liberalism encroaching upon the culture. “We shouldn’t be running a victory lap every time some sort of traditional value gets undercut,” he once told me. When he was a naval officer in the late 1970s, Bannon, a voracious autodidact, embarked upon what he described as “a systematic study of the world’s religions” that he carried on for more than a decade. Taking up the Roman Catholic history first instilled in him at his Catholic military high school, he moved on to Christian mysticism and from there to Eastern metaphysics. (In the Navy, he briefly practiced Zen Buddhism before wending his way back to Catholicism.)

Bannon’s reading eventually led him to the work of René Guénon, an early-20th-​­century French occultist and metaphysician who was raised a Roman Catholic, practiced Freemasonry, and later became a Sufi Muslim who observed the Sharia. There are many forms of traditionalism in religion and philosophy. Guénon developed a philosophy often called “Traditionalism” (capital “T”), a form of anti-modernism with precise connotations. Guénon was a “primordial” Traditionalist, who believed that certain ancient religions, including the Hindu Vedanta, Sufism, and medieval Catholicism, were repositories of common spiritual truths, revealed to mankind in the earliest age of the world, that were being wiped out by the rise of secular modernity in the West. What Guénon hoped for, he wrote in 1924, was to “restore to the West an appropriate traditional civilization.”

Guénon, like Bannon, was drawn to a sweeping, apocalyptic view of history that identified two events as marking the beginning of the spiritual decline of the West: the destruction of the Knights Templar in 1312 and the Peace of Westphalia in 1648. Also like Bannon, Guénon was fascinated by the Hindu concept of cyclical time and believed that the West was passing through the fourth and final era, known as the Kali Yuga, a 6,000-​­year “dark age” when tradition is wholly forgotten.