Benjamin Franklin was sent to investigate a miracle healer who could cure disease with invisible forces.
What he discovered changed science forever.
Paris, 1784. The city was obsessed with a German physician named Franz Mesmer who claimed he could cure anything—paralysis, blindness, seizures, chronic pain—using an invisible force he called “animal magnetism.”
Mesmer’s treatments were theatrical spectacles. Patients sat in dimly lit rooms around a wooden tub filled with water, iron filings, and glass bottles. Iron rods protruded from the tub. Patients would grasp the rods while Mesmer, dressed in flowing silk robes, moved among them, waving his hands, staring intensely into their eyes, and speaking in low, commanding tones.
And then something extraordinary happened.
Patients would fall into trance-like states. They’d convulse. They’d cry out. They’d report feeling waves of energy flowing through their bodies. Some would collapse unconscious. Others would claim instant healing from ailments they’d suffered for years.
Women especially seemed susceptible to Mesmer’s treatments—which led to whispered scandals about what exactly was happening in those darkened rooms when the doctor placed his hands on female patients and stared deeply into their eyes.
But scandal or not, people kept coming. Because people kept getting better.
Or so they claimed.
Mesmer hadn’t always been so theatrical. When he’d first developed his theory of “animal magnetism” in the 1770s, he’d used actual magnets—believing he could manipulate an invisible fluid-like force flowing through all living things, restoring balance and curing disease.
Then he realized he didn’t need the magnets at all. He could achieve the same results with just his voice, his hands, his eyes. The “magnetic force” wasn’t in the magnets. It was in him.
He became convinced he possessed a special power—that he was a conduit for this universal energy.
The Vienna medical establishment thought he was either a fraud or insane. They ostracized him. So Mesmer moved to Paris in 1778, where he became an overnight sensation.
Parisian high society couldn’t get enough. Mesmer’s waiting list stretched for months. Other practitioners adopted his methods, calling themselves “magnetizers” and later “mesmerists.” Clinics opened across the city.
But the French scientific and medical communities were skeptical. They’d seen plenty of miracle cures come and go. Mesmer’s claims sounded like mystical nonsense.
Yet his patients swore by him. Testimony after testimony described impossible healings. Were all these people lying? Delusional? Or was there something real happening?
King Louis XVI decided to settle the matter once and for all.
In 1784, he assembled a royal commission to investigate mesmerism scientifically. The panel included some of the greatest minds in France—and one very famous American.
Benjamin Franklin was 78 years old, serving as American ambassador to France. He was also a scientist, inventor, and one of the Enlightenment’s leading voices for rational inquiry over superstition.
Joining him was Antoine Lavoisier—the father of modern chemistry, the man who’d discovered oxygen and revolutionized scientific understanding of combustion and chemical reactions.
Also on the commission: Jean Sylvain Bailly (astronomer), Joseph-Ignace Guillotin (physician who’d later lend his name to the execution device), and several other prominent scientists and doctors.
Their task: determine if animal magnetism was real.
The commission watched Mesmer’s treatments. They observed the trances, the convulsions, the dramatic healings. Impressive theater, certainly. But was it medicine?
Then they did something revolutionary.
They designed experiments to test whether the “magnetic force” actually existed—or whether patients were responding to something else entirely.
In what may have been the first blind trial in scientific history, they had subjects tested without knowing whether they were actually being “magnetized” or not.
A mesmerist would stand behind a door, supposedly directing magnetic forces at a subject on the other side. The subject, not knowing if the magnetizer was actually there, would report feeling the effects—even when nobody was behind the door at all.
Trees were “magnetized” and subjects told which ones. They’d feel powerful effects from trees that hadn’t been magnetized—and nothing from trees that had.
Patients were blindfolded and told they were being magnetized when they weren’t. They’d respond dramatically. Then they’d be actually magnetized without being told—and feel nothing.
The pattern was unmistakable. Patients responded when they believed they were being magnetized—regardless of whether anything was actually being done to them.
The commission published its findings later in 1784.
There was no scientific evidence for “animal magnetism.” It didn’t exist. The invisible fluid flowing through all things was imaginary.
But something real was happening. Patients were responding—genuinely responding—to their own expectations, imagination, and the power of suggestion.
The commission had just documented what would later be called the placebo effect. They’d proven scientifically that belief alone could produce real physiological responses—that the mind could affect the body in measurable ways, even without any actual medical intervention.
This was revolutionary. Not because it vindicated Mesmer—it didn’t. But because it revealed something profound about human psychology and the healing process.
Mesmer was furious. He denounced the commission as biased, corrupt, closed-minded. His followers rallied to his defense, pointing to all the people who’d been healed.
But the damage was done. The craze began to fade.
Mesmer left France and resumed practicing in Switzerland. Eventually, he returned to the German state of Baden, where he died in 1815 at age 80—largely forgotten, his grand theory discredited.
But “mesmerism” didn’t completely die.
It lingered throughout the 19th century, experiencing periodic revivals. In the 1840s and 1850s, mesmerist shows were wildly popular in America—traveling performers would put volunteers into trances and have them perform stunts on stage.
Medical researchers, meanwhile, had noticed something useful: those trance states Mesmer induced were real, even if animal magnetism wasn’t. Patients in those states really did become unresponsive to pain. Really did become highly suggestible.
By the late 1800s, scientists had refined these techniques into what we now call hypnosis—stripping away Mesmer’s mystical theories while keeping the practical therapeutic applications.
Today, hypnotherapy is a legitimate medical tool used for pain management, anxiety treatment, and breaking habits. It’s not magic. It’s not mysterious cosmic energy. It’s the power of focused attention and suggestion—the same power Mesmer stumbled upon while waving his hands in darkened rooms.
And we still use his name. When something captures our complete attention, when we’re utterly transfixed and absorbed, we say we’re “mesmerized.”
Every time you use that word, you’re referencing an 18th-century German doctor who convinced himself he could channel invisible cosmic forces—and accidentally helped pioneer the scientific study of the placebo effect and the power of the mind over the body.
The 1784 royal commission didn’t just debunk a quack. It established a template for how to investigate extraordinary claims scientifically. It showed how to design experiments that could separate real effects from imagined ones.
Franklin and Lavoisier didn’t just prove Mesmer wrong. They demonstrated how science should work—with controlled experiments, blind trials, and reproducible results.
And they revealed something Mesmer never understood: he wascreating real effects in his patients. Just not the ones he thought.
The invisible force wasn’t flowing from him to them. It was flowing from their minds to their bodies—from belief to experience, from expectation to reality.
Mesmer thought he’d discovered a cosmic energy. What he’d actually discovered was the power of the human mind to heal and harm itself through belief alone.
That turned out to be far more interesting—and far more useful—than animal magnetism ever could have been.
So the next time something leaves you utterly mesmerized, remember: you’re experiencing a trace of that same mental power that convinced 18th-century Parisians they were being healed by invisible fluids flowing through magnetic rods.
The power was real. The theory was nonsense. But the word survived.
And so did the lesson: extraordinary claims require extraordinary evidence. Even when the patients swear it works. Even when the healer believes in their own powers.
Especially then.
Benjamin Franklin helped prove that in 1784. And we’ve been applying that principle ever since.