A Brief History of Creation (8 page)

M
OST PEOPLE
in the seventeenth century had a hard time accepting the existence of things that could not be seen by the naked eye. Many of van Leeuwenhoek's claims were initially dismissed, even by the most learned of the time. Worse, for him, was the ridicule. Some of it came from the English satirist Jonathan Swift, who liked to poke fun at scientists. Van Leeuwenhoek's observation of parasites that fed on fleas inspired this parody by Swift:

The vermin only tease and pinch

Their foes superior by an inch
.

So Naturalists observe, a flea

Has smaller fleas that on him prey
,

And these have smaller still to bite 'em

And so proceed ad infinitum
.

Yet nothing could have prepared van Leeuwenhoek for the incredulity that would greet his first great discovery, the microscopic world he examined in Berkelse Mere. It was a landmark moment in science. No other person had ever observed the tiny creatures that would later be understood to be protozoa and bacteria. Nor would anybody see them, without van Leeuwenhoek's personal assistance, for the rest of the century. He was the first human being to see a single-celled organism—a discovery for which he would forever be remembered as the father of microbiology. He called these tiny creatures “animalcules,” or “little animals.” He estimated that his tiny sample of lake water contained millions of them.

Van Leeuwenhoek was at first reluctant to share the discovery. More than a year passed before he finally described the animalcules in a letter to Oldenburg. Van Leeuwenhoek had guessed, correctly as it turned out, that he would not be believed. To most people in the late seventeenth century, the existence of creatures so small was beyond imagining. Many thought he was literally insane. Their suspicions only grew when van Leeuwenhoek would not provide them with a microscope capable of verifying what he had seen. Not until his later years, when his notoriety began to attract famous visitors, even royalty, did he give away some as gifts. Even then, the recipients complained that those they were given didn't work like the ones they had gazed through in van Leeuwenhoek's home.

If van Leeuwenhoek would not send his microscopes to them, then the Royal Society decided it would go to his microscopes. A delegation of several prominent British and Dutch clergymen arranged to travel to Delft. They eventually confirmed van Leeuwenhoek's claims. Within a few years, his reputation soared among the international scientific community. In 1680, the Dutch haberdasher became a full member in the Royal Society. He never attended a meeting, though, not even his own induction ceremony.

Four years after his observations of Berkelse Mere, van Leeuwenhoek made another monumental discovery. While examining his own saliva, he decided to look at the plaque between his teeth, which he described as “a little white matter, which is as thick as if it 'twere batter.” There again, he discovered animalcules, little string-like creatures he described as looking like tiny eels. He judged he had seen a thousand in a bit of plaque “no bigger than a hundredth part of a sand-grain.”

Soon, he was examining the dental plaque of almost everyone who would participate. In an old man who “never washed his mouth his entire life,” he found plaque swarming with animalcules. Yet in the plaque of another old man, “whose teeth were uncommon foul,” he found none. He guessed—probably correctly—that the absence of animalcules was because the man was so fond of wine and brandy. In a letter to the Royal Society that became one of his most famous, van Leeuwenhoek wrote “that all
the people living in our United Netherlands are not as many as the living animals that I carry in my own mouth this very day.” He wondered if the knowledge of their existence would prove too much for people to bear.

This was to be one of van Leeuwenhoek's greatest discoveries. Already the first to see simple one-celled organisms, he had just discovered the existence of bacteria, among the oldest forms of life on the planet and the source of so many diseases and infections. Of course, nobody then understood the true significance of what he had seen, or that it would, two hundred years later, contribute to a revolution in medicine.

At the time, his contemporaries were much more concerned with the question of where van Leeuwenhoek's animalcules came from. Spontaneous generation was seized upon as a possible method for microbes to propagate themselves, but van Leeuwenhoek suspected differently. Francesco Redi's
Experiments on the Generation of Insects
had been published in 1668, and the book had a strong impact on van Leeuwenhoek. He became convinced that Redi was correct, and that all life came from an egg. Some of his earliest letters contained thinly veiled attacks against spontaneous generation. “It was just as impossible,” wrote van Leeuwenhoek in a 1686 letter, “for a louse or a flea to come into being without procreation as it is for a horse or an ox, or some such animal to be born from the decay and corruption of a dung heap.”

Many of van Leeuwenhoek's investigations revolved around the subjects covered in Redi's book. What Redi had deduced through experiment, van Leeuwenhoek actually showed through the lenses of his microscopes. There, clear as day, anyone could see the eggs of flies or lice or fleas, or any of those creatures once thought eggless and parentless.

But in seemingly proving Redi correct, van Leeuwenhoek had settled one question, only to pose another that would prove far harder to answer. Tiny insects did indeed have eggs, but what of these far tinier animalcules? Not even he could claim to have seen their eggs.

To most people, the very idea of van Leeuwenhoek's animalcules fornicating seemed ludicrous. Spontaneous generation seemed a much more likely explanation, but van Leeuwenhoek was skeptical. He steadfastly asserted that these tiny beings reproduced the same way most
creatures did. He even convinced himself that he could see them in the act of copulation.

As a natural philosopher, van Leeuwenhoek was cast from the mold of Aristotle. He was an observer, not an experimentalist like Redi. But as his successes stacked up, he became more comfortable with his own knowledge and confident in advancing his own theories. He decided to settle the question of the animalcules' reproduction by doing something he almost never did. He devised an experiment.

The experiment van Leeuwenhoek came up with was simple. He took a pair of glass tubes and filled them with rainwater and ground pepper, a mixture he always found teeming with microscopic life. He heated both, which he knew from experience would kill the animalcules. Then he used the flame to completely seal one of the glass tubes. Without air, he imagined, nothing would be able to survive in the sealed tube. Two days later, he examined the tubes. As expected, the microorganisms had reappeared in the open tube. But when he unsealed the second tube, he was surprised to find them present there as well. The simplest explanation was that the creatures in the sealed glass tube had spontaneously generated.

Van Leeuwenhoek never did bring himself to accept the easy explanation that the microbes he observed in the sealed tube had been spontaneously generated. Though he dutifully reported his results to the Royal Society, he was unsure what to make of them. For the most part, he simply moved on.

I
N 1698
, Peter the Great, tsar of Russia and one of the most powerful monarchs in the world, embarked on a tour of the Netherlands to inspect the military capabilities of his allies. A riverboat carried him through the canals from the Hague and into Delft, where he dispatched two of his adjuncts to van Leeuwenhoek's home to invite him to visit. Peter would have gone himself to van Leeuwenhoek, the men explained, but the tsar didn't like crowds. When they met on the tsar's boat, van Leeuwenhoek was delighted to find that Peter spoke perfect Dutch. He brought the monarch a gift, a microscope upon which had been fastened the tail of an eel
so that he could see for himself the process of blood circulating. The tsar was delighted. Van Leeuwenhoek told acquaintances that he had found the encounter rather boring.

Van Leeuwenhoek had by then become one of the most famous men in the world. He had discovered hosts of microbial creatures. He was the first person to see spermatozoa in semen, and he was one of the first to see blood flow through capillaries, which he described in great detail. He had even described things as small as a single cell. In a 1692 essay on the state of microscopy, Hooke complained that the field had been “reduced almost to a single Votary, which is Mr. Leeuwenhoek; besides whom I hear of none that make any other Use of that Instrument except for Diversion and Pastime.”

The accolades were never enough for the Dutchman. Even into his later years, van Leeuwenhoek complained to anyone who would listen about the ill treatment that had greeted his earliest and greatest discoveries. He kept working into old age and continued his correspondence with the Royal Society and others. But even those letters often betrayed a kind of bitterness that had long since passed being appropriate. He would frequently provide lists of “witnesses” to confirm even the most mundane observations, even though his reputation was, by then, long beyond reproach.

By 1723, van Leeuwenhoek was suffering from increasingly violent lung spasms that made it hard for him to breathe. He began writing about his condition in a series of letters to the Royal Society. Though blind by then in one eye, he accompanied these letters with microscopic investigations of the midsections of sheep and oxen. Physicians attributed his episodes to a bad heart, but van Leeuwenhoek thought their diagnosis wrong. It turned out the doctors were, indeed, mistaken. Van Leeuwenhoek had a rare condition called respiratory myoclonus, which would later come to be commonly known as Leeuwenhoek's disease.

He had a friend translate his last two letters to the Royal Society into Latin, one of the languages he had never mastered. The letters had a certain macabre character. Approaching ninety years of age, van Leeuwenhoek knew he was dying, yet he approached his end very clinically. One of his letters described a fit that lasted three days, “during which time my
stomach and guts ceased to perform their office and motion, so that I was persuaded I stood at death's door.”

Van Leeuwenhoek's condition gradually worsened. By August 1723, he was dead. He was buried in a cemetery in Delft, just yards from the grave of Hugo Grotius, the religious theorist whose ideas had formed the theological underpinning of the Methodist and Pentecostal movements, and one of the most important figures in the history of the Netherlands.

Van Leeuwenhoek left his most prized possession to the Royal Society: a beautiful black-lacquer box that housed twenty-six silver microscopes, upon which he had permanently affixed specimens, all arranged like the “cabinets of curiosities” that were so popular during the era. On receipt, a clerk at the Royal Society dutifully recorded the contents in almost poetic fashion: “The eye of a Gnat . . . Globules of Blood, from which its Redness proceeds . . . The Vessels in a leaf of Tea . . . The Organ of Sight of a Flie.” The bequest was accompanied by a letter from a friend of van Leeuwenhoek asking that, upon receipt of the cabinet, the society send word to van Leeuwenhoek's daughter, Maria, “a spinster of excellent repute, who has preferred a single life to matrimony, in order that she might ever continue to serve her father.” In 1739, Maria van Leeuwenhoek had a small monument erected to her father in the cemetery where he lay. Six years later, she was buried by his side. She had never married.

Antonie van Leeuwenhoek is remembered as the “father of” a host of scientific disciplines and subdisciplines—most important among them, microbiology.
^*
That he began as merely a simple tradesman makes his accomplishments all the more extraordinary. After his work was done, the world became a much grander place, filled with an infinite array of microscopic life that no human being before him had ever guessed existed.

The implications for humankind's understanding of the origin of life were enormous. Van Leeuwenhoek was a deeply religious Calvinist. Life, for him, was the work of God's hand alone. Such beliefs were held by almost everyone at the time, and they did little to prejudice him against spontaneous generation. His advocacy of the observations of Francesco Redi is
what led van Leeuwenhoek to try to shut the door on the theory of spontaneous generation. Yet van Leeuwenhoek's experiments opened up an entirely new and even more contentious debate that would consume some of Europe's greatest scientific minds until the late nineteenth century: the debate over the possibility that
microbial
life could arise spontaneously. For the next two hundred years, some of the greatest scientific minds in the world would grapple with the question of just what had taken place in the spontaneous-generation experiments of van Leeuwenhoek and others. Soon the question was going to take on important religious implications, finding itself at the center of a debate between those who believed in a creator God and those who saw life as something that nature was capable of creating on its own.

*
Nearly 400 years after his death, a poll taken by a news organization in the Netherlands named van Leeuwenhoek the fourth greatest figure in Dutch history, ahead of Rembrandt and van Gogh.