“You mean—you were lying?” Wonder Woman asks Steve Trevor, a hero and a spy, in the new film that takes her name. The Amazon takes a moment to register his deception; the princess of Themyscira, having come to the world of men from the idyllic Paradise Island, is not accustomed to such manipulation. She pauses. “How do I know you’re not lying to me right now?”

With that, the superhero removes a weapon from her belt: a shimmering rope, golden in color and liquid in movement. She tosses her Lasso of Truth around Steve. He is powerless against it. “I’m taking you to the front,” he admits, robotically. “We are probably going to die.”

Wonder Woman is set at the height of World War I, but is otherwise a decidedly modern movie: It stars a woman (Gal Gadot) and treats a man, Steve (Chris Pine), as its damsel-in-distress. It has managed, even before its release, to enrage men’s-rights activists, which is quickly becoming a reliable measure of a movie’s modernity. So Diana Prince, daughter of Hippolyta, queen of the Amazons—a character who neatly combines the myths of ancient Greece with aspirations of contemporary America—fits fairly seamlessly into this moment of ever more normalized, and ever more commercialized, feminism.

But the character suits the times in another way, too, not just because of the fights she fights, but also because of one of the weapons she uses to fight them: the Lariat of Hestia, otherwise known as the Golden Lasso, otherwise known as the Lasso of Truth. The device was forged of the chain mail worn by Diana’s mother, the warrior queen; if someone finds themselves ensnared within the lasso’s golden grip—as Steve learns in the new Wonder Woman—that person will be compelled to tell the truth. The lasso features prominently in the director Patty Jenkins’s film, as both a weapon and a tactic: In it, Diana uses the glimmering device repeatedly to whip, to entrap, to win. Most of all, though, she uses it for precisely the purpose its name suggests: to force people, usually against their will, to admit to reality.

The golden rope, in that way, connects the Wonder Woman of 2017 to her comic-book origins. When the character debuted in 1941, as the second of the world wars raged around her, she was a paradox incarnate: The Amazonian princess was a warrior whose purpose was peace. The character was created by William Moulton Marston, a veteran of World War I who was also a professor, a lawyer, and a scientist. Marston held three degrees from Harvard, one of which was a PhD in psychology; his graduate work had involved conceiving of ways to measure human emotion. He was especially interested, though, in finding ways to detect deception. (Jill Lepore, who wrote a book on the origins of Wonder Woman, summed it up like so: “He was obsessed with uncovering other people’s secrets.”) In that work, Marston had created the systolic blood pressure test that could be used, he argued, to determine whether people were lying—making him one of the several scientists who could claim to have invented the era’s ultimate answer to the quantified lie: the polygraph machine.

Marston was also extremely adept at the art of self-promotion. Since so many could claim to have been the inventor of the lie detector—Marston, Geoffrey C. Bunn notes in his book The Truth Machine, once remarked that there were as many inventors of the lie detector “as there were monks, in the old days, who claimed to possess a piece of the true cross”—the psychologist set about ensuring that history would remember him as the primary of the claimants. Marston wrote a blurb for the Harvard Class of 1915 25th Anniversary Report noting that he had “had the luck to discover the so-called Marston Deception Test, better known as The Lie Detector.” He made himself the subject of several laudatory articles in the popular press. (One of them, a Boston Sunday story published in 1921, was headlined, “New Machine Detects Liars, Registers Emotion Scientifically; Traps Shrewdest Criminals.” It credited “William Moulton Marston, Boston lawyer-scientist,” with the creation of the device and announced, over-optimistically, that “successful lying will soon be a lost art.”) In 1938, as a capstone to the press coverage, Marston published a book. Its title? The Lie Detector Test.

Marston was capitalizing on one of his time’s many similarities to our own: His was an age that, too, was anxious about the future of truth. In America, in the decades between the world wars, propaganda had revealed itself to be a powerful weapon. (Walter Lippmann, the era’s expert on strategically employed information both in war and in other settings, published Public Opinion in 1922.) At the same time, as broad Progressive reforms swept the country, the American police further professionalized, emphasizing data and science in their work both tracking and solving crimes. Wonder Woman’s lasso was a golden embodiment of all that: It promised that, if we could just find the right tools, the truth would reveal itself, compulsorily.

Her lasso made its debut in the sixth issue of Sensation Comics, the DC series that ran between 1942 and 1952. The device came with a detailed backstory: The weapon, the issue explained, came from the chain links of the magic girdle worn by Queen Hippolyta. Once Diana was given the gift, she was visited by the goddesses Aphrodite and Athena, who imbued the hand-me-down with its truth-demanding capabilities. Wielding the lasso, then, Wonder Woman was a warrior who was also an investigator. “Like the equally mythic lie detector upon which it was modeled,” Bunn argues in The Truth Machine, “the lasso was intended to be one of Wonder Woman’s principal weapons against the forces of crime and injustice.”

In many ways, the mythic lie detector was also an allegory—for feminine charm, for the kind of soft power women can have, he thought, over men. The lasso was, after all, imbued with its mystical properties by the goddesses both of wisdom and of love. And it derived, in more practical settings, not only from Marston’s obsession with truth-telling, but also from his interest in related themes—among them power, submission, and bondage. Wonder Woman, Comic Book Resource’s Brian Cronin notes, “ended up tied up in chains so many times in the early years of the series that National Comics had to tell Marston to stop chaining her up so much.” (“They were not,” he adds, “objecting to her being tied up so much as the redundancy of him using chains all the time.”)

Despite all that, though, Marston was a feminist: He believed that a world that gave women more power—politically and otherwise—would be more peaceful, more empathetic, more worthy. Marston partly patterned Wonder Woman, Lepore suggests, after his student Olive Byrne, whom he taught at Tufts and with whom he fell in love; Marston, his wife Elizabeth Holloway, and Byrne lived together, a family ahead of its time, with their multiple children. Byrne was also the niece of Margaret Sanger; in 1916, Sanger and her sister, Ethel Byrne—Olive’s mother—had opened the United States’s first birth-control clinic.

Marston, savvy as he was when it came to popular storytelling, intended his character to be a tool of political persuasion: “Frankly,” he once put it, “Wonder Woman is psychological propaganda for the new type of woman who should, I believe, rule the world.” A press release about the character was slightly more subtle about it: “‘Wonder Woman’ was conceived by Dr. Marston,” it wrote, “to set up a standard among children and young people of strong, free, courageous womanhood; to combat the idea that women are inferior to men, and to inspire girls to self-confidence and achievement in athletics, occupations and professions monopolized by men.” The document added that “the only hope for civilization is the greater freedom, development, and equality of women in all fields of human activity.”

Wonder Woman’s lasso is part of all that: A shared concept of truth, of course, is another thing that must be had if there is to be any “hope for civilization.” And truth and deception, fittingly, are key themes in Jenkins’s latest cinematic rendering of Wonder Woman. The character who is also sometimes known as the Goddess of Truth is, in the movie, repeatedly deceived. Her love interest is a spy, which is to say a professional liar. “What one does when faced with the truth,” Diana muses, in a voiceover at the outset of the film, “is more difficult than you would think.”

And so Wonder Woman is a work that is decidedly at home, across its dimensions, in the world of 2017—a world that is on the one hand newly recognizing women’s widespread capabilities, but that is on the other deeply anxious about “alternative facts,” about “fake news,” about politically weaponized lies, about falsehoods that are uttered with no seeming consequence. The princess’s lasso, that shimmering metaphor for objective truth, is a symbol of aspiration; seen in another way, though, it is a symbol of despair. Here, in this wobbling weapon, is “wonder” as in awe; here, too, is “wonder” as in uncertainty. Here is a tool of truth that is decidedly ambivalent about its own powers. “How do I know you’re not lying to me right now?” the princess asks the spy. And the only way she can know for sure is to trust, paradoxically, in magic.