Antoni van Leeuwenhoek didn’t go to college and didn’t speak Latin (the language of scholars), but when he looked through his microscope

What if, popping into view in the strangest places, you could suddenly see moving, dancing, spinning creatures where you’d never seen them before? You look in a bucket of water—there they are. You look in a pond, in a puddle, on your skin, even at the plaque between your teeth, and they’re there too—in different shapes, with different moves, but uncannily, unmistakably alive. You don’t know what to call them, but you’re the first Earthling ever to see what the overwhelming majority of creatures on our planet look like, and for a little while, you’re the only one—the only one who could gaze down at the sweep of nature’s magnificence. What would that be like? Would you be frightened? Mystified? Joyous?

This actually happened. All at once, sometime in the early 1670s, one man took the first deep dive into our microbial world. He wasn’t a scholar, a philosopher, or a scientist. He ran a small fabric shop in Holland. He also sold ribbons and buttons. In his spare time, he got good at grinding lenses, so he made himself an eyeglass that could magnify 270 times. For its day, it was the best microscope in the world—ten times more powerful than any other. But most of all, and unlike most of his neighbors, he wanted to see; he was a deeply curious man. And that made all the difference.

Antoni van Leeuwenhoek

 
PHOTOGRAPH BY PETER HORREE, ALAMY

According to my blog colleague Ed Yong, who describes this in his new book, Antoni van Leeuwenhoek didn’t go to college and didn’t speak Latin (the language of scholars), but when he looked through his microscope, he got giddy with astonishment. Right away, he wanted people to know that there was a vast community of “animalcules,” as he called them, everywhere.

So he sent his descriptions to the most prestigious scientific society of his day, the Royal Society in London. Apologizing for his crude language (“pray take not amiss my poor pen”), he told them what he’d seen, in one letter, then another, then another ...

In an ordinary drop of water, he wrote, he’d found “little eels, or worms, lying all huddled up together and wriggling … the whole water seemed to be alive with these multifarious animalcules.” (Hello, bacteria!)

ILLUSTRATION BY ROBERT KRULWICH

Ewww. Was he disgusted? Horrified? This was rainwater, after all.

Not at all: “ ... I must say, for my part, that no more pleasant sight has ever come before my eye than these thousands of living creatures, seen all alive in a little drop of water ...”

A Miniature Horse-Headed Thingy

In another letter, he describes a roundish critter that “stuck out two little horns which were continuously moved, after the fashion of a horse’s ears [and with a body that ended in a tail].” (Hello, microbe we now call a protist!)

According to the science writer Leonard Mlodinow, who also tells Leeuwenhoek’s story in his new book, when the Dutch shopkeeper’s letters were read to the society’s members, some were intrigued. Others scoffed. What does this Dutchman know, they said. They wanted to see for themselves.

Leeuwenhoek wouldn’t send them his microscopes; he was jealous of his craft. But he did send affidavits from a Dutch public notary, a barrister, and his local minister. Gradually, the invisible world he described began to find an audience.

Knock, Knock—It’s the Czar

One day in the spring of 1698, two foreign gentlemen knocked on his door and announced that the czar of Russia, Peter the Great, was at that very moment waiting on board his royal ship in the nearby River Schie, hoping to meet the shopkeeper. He would have come on his own, his servants said, but he worried that appearing on the streets of Delft might cause a commotion, so he asked Leeuwenhoek to grab a couple of samples and join him on board. Leeuwenhoek took a live eel and a couple of microscopes and spent two hours with the czar gazing at blood rushing through the capillaries of the eel’s tail. His critics grew quiet. Leeuwenhoek was becoming famous.

ILLUSTRATION BY ROBERT KRULWICH

Perhaps his most celebrated letter describes, as Yong puts it, “the white, batter-thick plaque lodged between his teeth.” Leeuwenhoek scraped some plaque out of his own mouth, took a look, and was gobsmacked. His teeth were covered, he found, with active creatures.

“ … there were many very little living animalcules, very prettily a-moving. The biggest sort … had a very strong and swift motion, and shot through the water (or spittle) like a pike does through the water. The second sort … oft-times spun round like a top … and these were far more in number.”

He also scraped plaque from two willing lad