The Theater of Nature

What van Leeuwenhoek accomplished.
How he was received by the people of his time.
What happened to his microscopes.

After his election as a Fellow of England's Royal Society in 1680, when he was 47, Antony van Leeuwenhoek entered the prime of his career. By then, he had seen red blood corpuscles and sperm cells in a variety of animals, including man, as well as what we now call protozoa and bacteria. He had written several dozen letters to the Royal Society, and excerpts from about half of them had been published in the Society's journal, Philosophical Transactions.

He didn't stop there. Over the next forty years, van Leeuwenhoek sent several hundred letters to the Royal Society. By his death in 1723, all or parts of almost a hundred and twenty letters had been translated and published in Philosophical Transactions in just over a hundred articles. Van Leeuwenhoek was their most published author, by far.

In addition, he wrote over a hundred letters that were not published in Philosophical Transactions and were addressed to the wide range of correspondents that his fame brought him. Van Leeuwenhoek published these letters himself in Dutch and Latin as detailed on the Publications page.

Almost all of van Leeuwenhoek's letters were accompanied by illustrations, and the letters referred to them. He employed anonymous artists (called limners or draughtsmen) to draw them. They were then re-drawn on copper plates by etchers in London for Philosophical Transactions and Holland for his self-published volumes, and finally printed as reverse images on paper. Compared to the masterpieces that Robert Hooke drew himself for Micrographia, the drawings that van Leeuwenhoek provided are informative but less elegantly drawn.

In 1692, when as it turns out van Leeuwenhoek was not halfway through his long career, Hooke delivered a lecture about the history and future of both the telescope and microscope.

Much the same has been the Fate of microscopes, as to their Inventions, Improvements, Use, Neglect and Slighting, which are now reduced almost to a single votary, which is Mr. Leeuwenhoek;

besides whom, I hear of none that make any other Use of that Instrument, but for Diversion and Pastime, and that by reason it is become a portable Instrument, and easy to be carried in one's Pocket.

At the time, the astronomer Edmond Halley, ally of Isaac Newton, had been editor of Philosophical Transactions for volume 16, and van Leeuwenhoek had not had a letter published in seven years, since 1685. Halley and Newton had little use for microscopes and they were long-time opponents of Hooke, who was van Leeuwenhoek's chief proponent at the Society. Hooke continues:

If we enquire into the Reason of this Change of Humour, in Men of Learning, in so short a time, we shall find that most of those, who formerly promoted these Enquiries, are gone off the Stage; and with the present Generation of Men the Opinion prevails, that the Subjects to be enquired into are exhausted, and no more is to be done:

Besides they pretend that all the Discoveries that have been hitherto, or that can be made, for the future by these Instruments will afford no gainful profit, and all other Notions are insipid with them, besides such as bring ready Money.

All the other contemporary microscopists studied the microscopic structure of macro organisms, as did Leeuwenhoek, and perhaps those subjects appeared to be "exhausted". Van Leeuwenhoek alone discovered the living world of microorganisms, where the subjects were far from exhausted.

Halley was about to be replaced as editor of Philosophical Transactions by Robert Waller and then Hans Sloane, who would again begin publishing van Leeuwenhoek. Indeed, as Hooke predicted, there was much more to be done:

But those, who make such estimates, may, perhaps, find themselves very much mistaken in their Judgment, if the Subjects are duly prosecuted, as they are capable of so being.

For, as to the Discoveries that may be made in both Kinds, I conceive they are vastly greater, both for Number and Value, than those few that have been already made; and not only for the Information of the Intellect, but what answers their greater Objection, even for the increasing their Treasure.

While he was out of favor with editor Halley during those years, van Leeuwenhoek wrote dozens of letters, most of which he sent to the Society and by all accounts were not even acknowledged by Halley. Van Leeuwenhoek published them himself in parallel Dutch and Latin editions.

Hooke concludes that the microscope:

is become almost out of Use and Repute: So that Mr. Leeuwenhoek seems to be the principal Person left that cultivates those Enquiries. Which is not for Want of Considerable Materials to be discover'd but for Want of the inquisitive Genius of the present Age.

In fact, it would take more than a hundred years before the compound microscope would catch up to van Leeuwenhoek's in magnifying power and resolution. It would be even longer than that before scientists could put van Leeuwenhoek's microbiological discoveries into a context. They began re-discovering van Leeuwenhoek's protozoa and bacteria, related them in a Linnaean taxonomy, gave them names, and began understanding how van Leeuwenhoek's "animalcules" enabled human life and occasionally threatened it, i.e., "germs".

It comes down to this: van Leeuwenhoek had an instrument using a dead-end design that was an order of magnitude better than anyone else had. What he saw was very difficult for anyone else to see. He was so far ahead of his time that his discoveries had no context. What he saw, no one suspected, understood, or knew what to do with.

Unlike his contemporary Vermeer, whose death at an early age meant the loss of all the paintings he never lived to paint, van Leeuwenhoek discovered only things that were already there. Had he died early, everything that he discovered would have been discovered by someone else.

So van Leeuwenhoek's accomplishment, sustained for half a century, is as much an individual accomplishment as a scientific one. He had the leisure, the motivation, and the habits of mind that he needed. He was tenacious and honest, and he had an eye for the important detail.

What he discovered

Van Leeuwenhoek's own cabinet of nature was a little harder to display, but none the less varied than those of his friend Frederick Ruysch.

In hindsight, Van Leeuwenhoek's early discoveries of red blood cells, protozoa, bacteria, and sperm receive most of the attention. They also needed the strongest lenses to see, especially the bacteria.

However, van Leeuwenhoek reported his observations of a wide range of other curiosities and wonders. Harting's Het Mikroskoop in 1850 has a list, repeated in Haaxman's 1875 biography, of some of the specimens that were still attached to the hundreds of microscopes auctioned in 1747 after the death of Maria, van Leeuwenhoek's daughter. Harting grouped them.

For many of them, lenses magnifying between 100 and 200 times would have been appropriate for what van Leeuwenhoek wanted to see.

Famous visitors

Judging by the list of prominent visitors to his home (see right), van Leeuwenhoek was known and admired among the intellectual and political elite. Judging from his frequent complaints and attempts to control access to his house, van Leeuwenhoek was also known and admired among the curious who must have read his books and made the pilgrimage to Delft.

On January 14, 1710, he wrote:

The same Gentlemen had two other Scottish gentlemen in his company, all of whom I gladly received, and so will I do all those who have an introduction from Mr. Sloane. But if I should receive everyone who comes to my house, or tries to come, I should have no freedom at all, but be quite a slave.

And eighteen months later, on August 18, 1711:

You are displeased at not being welcomed at my house. I beg you please not to take it ill, seeing that we send off everyone who tries to visit me, unless they have some sort of introduction. ...

You were sent away especially because you were not known, and because some 8 or 10 days earlier no less than 26 people came to see me within four days, all of them with introductions (except a Duke and a Count, with their Tutor), which made me so tired, that I broke out in a sweat all over.

His Death

In the final year of his long life, van Leeuwenhoek wrote five letters and had them all translated into Latin before he sent them. Other than the 1679 letter about human sperm and the letter of January 15, 1721, these were the only letters published in Latin in Philosophical Transactions. However, for the thirty years he self-published his collected letters, they were all translated into Latin, so he certainly had access to translators.

His friend, publisher Reinier Boitet, described the scene (Dobell translation):

Six-and-thirty hours before his death, when his limbs were already growing numb, the fire of his ardour glowed still so bright, that, with lips stammering and well-nigh stiff, he directed his thoughts to be set down on paper regarding a kind of sand which a certain distinguished gentleman, a director of the East-India Company, had handed over to him, to find out whether any gold were concealed therein.

Van Leeuwenhoek summoned his friend Johan Hoogvliet, who wrote in his cover letter to Philosophical Transactions editor James Jurin:

Our venerable old van Leeuwenhoek, being already in the throes of death, though none the less mindful of his art, ordered me to be called to him; and raising his eyes, now heavy with death, kept asking me in half-broken words if I would translate these two letters out of our native tongue into Latin, and send them, most distinguished Sir, to you.

Philosophical Transactions editor James Jurin published them, in Latin, along with Hoogvliet's cover letter, in volume 32.

Van Leeuwenhoek died in Delft on August 26, 1723, just shy of his 91st birthday, of bronchial pneumonia.

His Will

Van Leeuwenhoek's first wife, Barbara de Meij, died in 1666, and his second wife, Cornelia Swalmius, in 1694, so he lived the last thirty years of his life as a widower.

He and Barbara had five children, but only Maria survived infancy. Maria, who never married, outlived her father by twenty years. She took care of van Leeuwenhoek for the last half of his life, had his memorial constructed in the Nieuwe Kerk, and outlived him by two decades. She is buried beside him.

According to an article by E.W. van den Burg and G.J. Leeuwenhoek first published in 1995, based on recent research of records from the city archives of Delft, van Leeuwenhoek left a small but still valuable estate.

His will, registered in 1712, named his daughter Maria as beneficiary. At her death in 1745, after deduction of expenses and bequests, van Leeuwenhoek's estate amounted to 59,389 guilders and 4 stuivers, and Maria's amounted to 15,289 guilders and 14 stuivers. It designated several relatives to receive obligaties, or bonds (see right). The will was revised a few times before his death and then before hers to account for the death of some of these beneficiaries.

As best I can tell, the other valuable possessions were his land, not only his house, but some adjacent and nearby property. I do not know how to translate 60,000 guilders into today's money. According to the same article, none of his close relatives left estates of a value even close to van Leeuwenhoek's, so it seems as those he was the most prosperous member of his family.

His sinecures amounted to 800 guilders per year, about what a City Secretary earned. Fifty years of these sinecures would thus have amounted to 40,000 guilders if he had saved every stuiver. Since there is not any record of his having inherited anything from others, this estate must have come from his investments in land and bonds. We do not know how long he maintained his drapery business or under what circumstances he stopped doing it. Did he sell it?

The article reports on documents from the Delft city archive:

Antoni Leeuwenhoek and Carel Serval together on May 8, 1708 buy from the heirs of Annetje Pieters van der Vis, widow of Pieter Jans Hofland, a house and yard on the north side of the Nieuwstraat in Delft, abutting on the east Pieter van der Wild and on the west said Carel Serval, stretching from the street to behind the mansion, previously having belonged to the widow of Mayor Joost van Lode Steijn and now belonging to Antoni said Leeuwenhoek. The purchase price is 550 guilders in cash.

Serval takes the front half with the house and its income. Van Leeuwenhoek takes the back half, which abuts the back of his property on the Hippolytusbuurt. The purchase price of a house and yard for 550 guilders in 1708 compared to an estate of 60,000 guilders two decades later suggests that van Leeuwenhoek was quite well-to-do by the end of his life.

The city archives also have a tax assessment record for seven guilders for a property on the east side of the Oosteinde at the corner of the Nieuwe Langendijk, which was owned by van Leeuwenhoek. The little we know about his parents and childhood suggest that he grew up on the Oosteinde. Perhaps he inherited this house from his father?

So one possible scenario is that his drapery business was prosperous enough to let him invest in the bonds and that he lived the last decades of his life on the interest. I welcome hearing from anyone with more information or a different scenario.

His Microscopes

He bequeathed twenty-six microscopes to the Royal Society. They were duly described and catalogued, only to have "disappeared" from the archives by the mid-1800's. The rest, his will stated, should be sold "in a bundel".

Of the three hundred, at least (some sources say five hundred), microscopes that van Leeuwenhoek made, only nine are known today, plus an aalkijker whose provenance is not completely certain. Of the hundreds of lenses that he made, only fourteen survive today. The Boerhaave Museum in Leiden has the largest collection in any one place, and its library has the best collection of works about van Leeuwenhoek.

In 2009, Christie's in London auctioned one of van Leeuwenhoek's microscopes that had been on display in the Boerhaave, estimating pre-sale a high bid of 100,000 euro. It sold for 313,250 euro, the highest price ever paid for a scientific instrument from the Dutch Golden Age and a testimony to the significance of van Leeuwenhoek today.

Van Leeuwenhoek's papers are lost. His will states:

It is our desire that in one box or suitcase will be closed up all the unpublished writings and letters, written by me, Leeuwenhoek, concerning my discoveries, and ten cut copper plates, belonging to some unpublished letters, for which was paid more than five hundred guilders as well as the translation into Latin, for which was paid seventy guilders and that so long as the villain [word deleted later by van Leeuwenhoek] Adriaan Beman is living, both those letters and those still to be written afterwards, may not be printed by his son or next of kin.

From 1693 to 1702, van Leeuwenhoek had published half a dozen volumes of letters printed by his next door neighbor Henrik van Krooneveld. For his Send-Brieven in 1718, he used Adriaan Beman, and that relationship apparently did not go well.

After van Leeuwenhoek's death, two other articles in Philosophical Transactions concerned him directly. Within a year, James Jurin published, in volume 32, "Some Account of Mr. Leeuwenhoek's Curious Microscopes, Lately Presented to the Royal Society. By Martin Folkes, Esq; Vice-President of the Royal Society".

Fifteen years later, Henry Baker wrote "An Account of Mr. Leeuwenhoek's Microscopes", which was published in volume 41, 1739. These two articles provide much of what we know about the microscopes, confirmed by direct analysis of the few surviving, which were probably not among those bequeathed to the Royal Society.

Van Leeuwenhoek today

Van Leeuwenhoek had no sons or brothers who survived to have children, so the surname is rare today. All the descendants come from the family of van Leeuwenhoek's uncle Huijch. Two of Huijch's sons, Lambrecht and Maerten, lived long enough to have sons. Today, the Dutch telephone books list only one private person with the "van" (an elderly widow who lives near Amsterdam) and about two dozen without it. They all still live near Delft.

There are a handful of businesses named after van Leeuwenhoek, and many, many streets. The Antoni van Leeuwenhoek Ziekenhuis, the cancer hospital in Amsterdam, was founded over a hundred years ago and named after him because "cancer" was a shunned word. The hospital is today the most common reminder of his name in everday Dutch life.

In 1877, the Royal Netherlands Academy of Arts and Sciences established the Leeuwenhoek Medal, awarded once each decade to the person judged to have made the most significant contributions to the "advancement of microbiology". Louis Pasteur won it in 1895.

Since 1949, the Royal Society in London has awarded and published an annual Leeuwenhoek Lecture on the subject of microbiology.

The city of Delft, saturated with Everything Vermeer, has put a plaque on the wall of the building -- still with the shop downstairs, housing upstairs -- that replaced van Leeuwenhoek's Gouden Hoofd. The city also has a small display case outside the room that he tended in the Stadhuis. And there is the memorial in the Oude Kerk. See the Biography page.

In a recent public poll to determine the "Greatest Dutch" men and women, van Leeuwenhoek finished fourth, ahead of other top-ten finishers Erasmus, Anne Frank, Rembrandt, and Vincent van Gogh. While the press coverage referred to van Leeuwenhoek's discoveries as baanbrekende, pioneering, it also called him ongeschoolde hobbyist, an uneducated dilettante.

Conclusion: How was he able to do it?

Van Leeuwenhoek did not inherit any wealth, so he had a day job -- his drapery business -- and he had two civic sinecures. Most importantly, he preserved his independence and autonomy by, in a passive way, controlling access to his time and his knowledge.

He did no teaching. He wrote to Leibniz on September 28, 1715:

To train young people to grind lenses, and to found a sort of school for this purpose, I can't see there'd be much use ... because most students go there to make money out of science, or to get a reputation in the learned world. But in lens-grinding, and discovering things hidden from our sight, these count for nought.

He had no professional affiliations beyond the Royal Society, and they were in England. He never visited their offices or attended a meeting, at which he would have been welcomed. Indeed, he never left Holland after he began researching.

While he took lots of suggestions, he had no supervision. He did it with his own money on his own time in his own way as an outsider to the politics of the academic and religious communities.

Leibnitz wrote to Christiaan Huygens on 2 March 1691:

I prefer a Leeuwenhoek who tells me what he sees to a Cartesian who tells me what he thinks.

Van Leeuwenhoek wrote on June 12, 1716:

I've spent more time than many will believe [making microscopic observations], but I've done them with joy, and I've taken no notice those who have said why take so much trouble and what good is it?

Equally importantly, van Leeuwenhoek lived at a time before the development of what we call "academic disciplines" and "science", a noble quest indeed, but one that has led to our world of increasingly narrow specializations, massive digitized data sets, hyper-competitive funding proposals, and an unreadable quantity of relevant publications.

If he were alive today, what would van Leeuwenhoek specialize in? If he had a job, an official position, an agenda of committee meetings, if he had to write funding proposals and work on teams and ask permission or get authorization to do everything he did, that is, if he were in our laboratories and classrooms today, sitting next to you, would he accomplish as much? Will you?

What do you do when you see things that no one has ever seen before?

Wat doe je als je dingen zie dat niemand ooit heeft gezien?

What motivated scientists before the introduction of institutional incentives?

My work, which I've done for a long time, was not pursued in order to gain the praise I now enjoy, but chiefly from a craving after knowledge, which I notice resides in me more than in most other men.