What We Think We Know
Nerves are the body’s electrical system. And the brain is the CPU. Or at least, that’s how we tend to think about it, isn’t it?
It sounds right. It feels right. It’s what we were taught. Electricity flows. Signals transmit. The body becomes a circuit, and the brain—the central command, the CPU—directs the show. It decides which wires fire, when and how, to satisfy its needs and wants. This metaphor—the nervous system as wiring—shows up in classrooms, clinics, and casual conversation. We don’t even notice it anymore.
But metaphors aren’t just decorative. They frame our thinking. They give us leverage—and they limit us. They clarify some things by obscuring others. They can sharpen insight, or quietly box us in.
So let’s look again. Not to dismiss the metaphor—nerves do conduct signals. But to make sure we haven’t inadvertently limited our understanding by embracing an idea that, it turns out, is not entirely accurate.
The Spark: A Leg Twitches in Bologna
The year is 1780. The place is Bologna, Italy. In the laboratory of a quiet, unassuming anatomist and physician by the name of Luigi Galvani.
Among the clutter of scientific tools of the day there lies a frog. Long dead. Dissected. The subject of research into the nature and operation of nerves. And a chance synchrony, a literal spark, changed the course of scientific discovery.
By dumb luck, an electrostatic generator in the room happened to emit a bright flash, a loud snap, right as the assistant touched their metal scalpel to the nerve of that inanimate frog. And in that moment, the circuit was completed, electricity flowed, and the muscles involuntarily contracted. The dead frog moved, almost as if it had been brought back to life.
It hadn’t, of course, but that didn’t stop the likes of Mary Shelley and her Frankenstein’s Monster from capturing the imagination of the world.
Galvani is not a man prone to theatrics. But this moment? It captivates him. He repeats it. Again, and again, and again. Imagine being a neighbor, seeing this seemingly eccentric professor hanging dead frogs from brass hooks along the iron balcony railing during storms so he could watch how it affects them. Because affect them they did.
In this seemingly macabre vision of lifeless bodies moving, nature is hinting at her profound secrets. Secrets she wants desperately to be known and understood. And Galvani answers the call.
From this, he draws a daring hypothesis: that electricity is not merely external. It’s not just spark and machine. It lives within the animal. The brain, he proposes, secretes a vital “electric” fluid. A separate and distinct form of electricity from that of the rest of nature, but one that is intimately related. It courses through the nerves. It animates muscle. It is, perhaps, the hidden engine of life itself.
Elegant. Intuitive. Radical.
Why He Believed It
It’s easy to smile at this from the future. A fluid? In the nerves? Really? But hey, now that we know how it really works, he wasn’t entirely wrong, was he?
But let’s take a moment and see the world as it existed so long ago. Forget everything you know, and step into the world of 1780. You have no voltmeter. No oscilloscope. No ion channel theory. You live in a world where light is conducted through space by something called an aether. And disease is cured by balancing “humors” or types of fluid in the body.
This isn’t superstition. It’s framing. It is an attempt to develop a deep and intuitive understanding of the world. Something I fear that the science of our day may have lost in their love of mathematical models and giving everything a name. Names that hide their meaninglessness by being little more than a description in a dead language, or named after a person to honor and remember their contributions. Sadly, names and formulas do not bring understanding of the deeper meaning of a thing any more than repeatedly describing what something does brings one closer to understanding why or how it does it.
No, let’s give credit where credit is due. Galvani wanted to fully and deeply understand and build a mental model for what was happening here. A mental model that honored his faith and his world view. But one that actually explains what he is seeing, not just describes it.
And let’s not lose sight of the fact that this mental model was a metaphor. Words meant to stand in for a deeper, admittedly unknown truth. He knew this. His contemporaries knew this. I’m afraid that maybe the modern mind has lost sight of this implicit fact. I know it took me a long time to realize this distinction. And to realize just how much value lies buried in these old ideas, if you see them not as literal truths dogmatically embraced, but as metaphors meant to shape thought and discourse.
His language, his framing, feels dated, maybe even superstitious to a modern audience. But he’s not guessing. He’s observing, testing, refining. He is the consummate scientist. He watches a frog’s leg twitch and asks—not what caused it, but where it came from. If metal alone were responsible, why does the effect vanish with identical metals? Why does the nerve itself seem to carry the signal?
He’s not trying to be revolutionary. He’s trying to be accurate. He follows where the data takes him. And he expresses that in the language of his day.
Oh if I could go back in time and warn my younger self about the dangers of taking language too literally. Every word is a metaphor, even those we think are supposed to be literal. Maybe then I wouldn’t have been so dismissive of the ideas of the past. Maybe then I would have been able to see through their eyes, really seen, and been the better for it. If only.
Ah, but wait, there’s more: reverence. Galvani sees life as sacred. Electricity, in his hands, isn’t just a force. It’s a whisper from the divine. He’s not wrong there, either.
The Divergence: Volta, and a Question of Origin
Meanwhile, 200 kilometers away, another man is inspired to replicate Galvani’s work. Alessandro Volta–professor of physics at the University of Pavia–sees the same frog, the same twitch, the same spark.
But he draws a different map.
To Volta, the cause is clear: it’s the metals. Dissimilar metals in contact, with moist tissue completing the circuit. The frog isn’t the source. It’s the detector.
The disagreement is profound—but the men are not adversaries. They write, they test, they argue with civility. This civility is so significant that Volta coins “galvanism” in Galvani’s honor, even as he builds the battery that will bear his own name, and which (supposedly) disproves Galvani’s thesis.
Each man’s idea sparks a revolution. Galvani points toward bioelectricity. Volta ignites electrochemistry.
So who was right? That’s the wrong question. Science isn’t a courtroom. It’s a conversation.
The Metaphor We Inherited
Over time, one metaphor wins out: nerves as wires. Not a unique form of electricity, but a simple conductor of the electricity we all know and love and have come to depend on.
It makes sense. It explains. It predicts. It works. It feels scientific in all the ways we want science to feel: precise, repeatable, clean.
But . . . it’s not quite . . . true.
Still, the metaphor stuck. And with it, an invisible assumption: that what we can model is all there is.
The Contradiction: Direction
You see, a wire conducts indiscriminately. Electricity can flow in either direction.
The same is not true of a neuron. The signal always and exclusively travels in one direction.
A neuron is structured like an uprooted tree. The roots are like the dendrites, collecting the signal and channelling it to the trunk, the axon. It travels upwards towards the branches, the axon terminals, where it is emitted like oxygen from leaves. Directional. One way. Always. No exceptions.
“Wait a minute!” you say. “The nerves send signals to the brain, and the brain sends signals to the muscles.” Indeed. But through different nerves, oriented in the other direction.
That’s the danger of a metaphor that is not a perfect match to reality. While it’s great for conveying the idea of signaling, it also runs the risk of making us believe things that turn out to be untrue. No, everything you ever learned about how electricity flows through wires: Nope, doesn’t apply here. It’s just a metaphor, and an imperfect one at that.
The Quiet Reframe: When Metaphor Becomes Belief
The problem wasn’t the metaphor. It was forgetting that it was a metaphor.
We all have this bad habit: Acceptance. Quiet, unquestioning acceptance. It’s what we heard first. Or what we’ve heard the most. Or we heard it from those we like, admire, or trust the most. So we accept it as unquestioned truth. Even the parts that we unknowingly injected ourselves — the things that were never said or intended by those we got it from. Our attempt to read between the lines, or add our own personal flourish to it. The problem: Sometimes we’re wrong.
And that’s the real problem. Sometimes metaphors, like questions, create the very box we want so desperately to think outside of.
Galvani did the opposite. He stayed curious.
Galvani’s Legacy: The Honest Error That Sparked a Field
Galvani was wrong. But beautifully so.
His “electric fluid” doesn’t exist. Not literally, anyway.
His conclusions were incomplete. Or at least, the way we understand them.
But his questions? That’s where the beauty, the genius, lay.
He gave us a way to think about life—not as clockwork, but as charge. Not as mechanism, but as possibility. But . . . I wonder . . . is there really a difference?
Nevertheless, from his spark came electrophysiology. Neurobiology. The very idea that information could move through tissue in pulses and waves.
He didn’t finish the story. But he began it. With rigor. With reverence. With frogs.