Antony van Leeuwenhoek

David F. Coppedge

It’s not often that a layman untrained in science makes a fundamental discovery, starts a new branch of science, and alters the course of human history. Nor is it often that a layman shows exemplary scientific technique that becomes a model for scientists to come. Antony van Leeuwenhoek was such a person. Extremely inventive, careful, and precise, unfettered by false notions of the day, Leeuwenhoek was driven by an insatiable curiosity that captivated him at age 40 and kept him going to his dying day at age 91. It started when he read a copy of Robert Hooke’s new illustrated book Micrographia in 1665, which contained drawings of insects, cork, textiles and other things revealed under a microscope at magnifications about 20-30x. Leeuwenhoek took to grinding his own lenses and making his own microscopes. Perfecting a technique that raised the power to over 200x, he opened up a whole new world never before seen by man: the world of microorganisms.

Born in Delft, Holland, Antony did not have any inclinations or opportunities to become a scientist. He would also know hardship and grief. His father, a basket maker, died when he was five or six. His mother was the daughter of a beer brewer. She remarried a painter and bailiff, but he died when Antony was 16. He was educated by an uncle, and never went to a university, never learned Latin (the scientific language of the day) or any other language other than his native Dutch. By age 16, he was apprenticed to a textile merchant, and he became a drapery shopkeeper before he was 22. He married Barbara de Mey, the daughter of a silk merchant about that time. The Leeuwenhoeks had five children, four of whom died young.

Antony became a chamberlain in 1660, later a surveyor and an inspector of the measures for wine. Through his appointments and possibly some inheritance, he attained a comfortable income with time to pursue what would later become his famous hobby. His wife died in 1666 when he was 34; five years later, he married Cornelia Swalmius, the daughter of another cloth merchant who was also a Calvinist minister. Her influence may somehow have stimulated Antony’s investigations into science, since these began within two years after their marriage. This second marriage lasted 23 years till her death in 1694; Antony was cared for by his last daughter till his death in 1723, thus carrying on his scientific work for an additional 29 years after becoming a widower a second time.

Leeuwenhoek did not invent the microscope (compound magnifying lenses were known 40 years before he was born), but he took it to new levels of power. He was probably acquainted with magnifying lenses used to investigate the textiles in his trade. His only trip to London (between marriages, in 1668) introduced him to the unseen natural world under the magnifying lens shown in Robert Hooke’s popular new book, Micrographia. We can only surmise what sparked his interest in microscopy that was in full bloom five years later; this book? His second wife or her intellectual friends? His own curiosity about nature? Somehow, he began grinding his own magnifying glasses, and perfecting a way to mount them and hold specimens in position for viewing. Though crude by today’s standards, they were nevertheless far superior to those used by Hooke, Swammerdam, Malphighi and others, and were unsurpassed until the 19th century. (The electron microscope would have to wait 250 years.) The compound microscopes of his day suffered from chromatic aberration and were not useful much above 20x. Leeuwenhoek made tiny lenses not much bigger than a pinhead in his simple microscopes, but aided with excellent eyesight, he achieved magnifications as high as 270x and 1.4 micron resolution. He was now in position to peer into a world never before seen by human eyes.

Other scientists of the day were content to magnify well-known objects like leaves and textiles. Leeuwenhoek wanted to see the invisible. By 1673, when he was finding exciting things with his microscope, a friend put him in touch with the Royal Society of London. Antony sent them drawings (made by a friend) of bee stings and mouthparts, a louse and a fungus. The eminent British scientists were at first skeptical of the claims by this untrained layman who only spoke Dutch. When in 1676 he described finding microorganisms in water that were so small that “ten thousand of these living creatures could scarce equal the bulk of a coarse sand grain,” the surprised Royal Society requested corroboration from other eyewitnesses, especially since Robert Hooke himself could not repeat them (until later, with a more powerful microscope). Several friends, including a pastor, and a notary public, sent affidavits that they also saw these things through Antony’s microscope. As Leeuwenhoek’s observations were found to be true and accurate, his reputation grew, and by 1680 this untrained layman was elected a fellow of the Royal Society. Though he would never revisit London or attend a meeting, the Dutch cloth merchant kept up a lively relationship with the British scientists for fifty years, sending them hundreds of letters with attached samples, some of which survive to this day in the Royal Society archives, along with a few of his hand-made microscopes; though out of hundreds he manufactured, only nine survive.

Artwork by J. Beverly Greene, commissioned for this biography. All rights reserved.

Leeuwenhoek’s letters sparkle with the excitement of discovery. Part of the fun of reading them is catching his infectious joy; where words like astonished, wonderful, odd, perfect, marvelous, inconceivable are frequent as he describes his “wee animalcules” and their motions. Describing protozoa and bacteria in a drop of fresh water, he writes,

The motion of most of them in the water was so swift, and so various, upwards, downwards, and roundabout, that I admit I could not but wonder at it.  I judge that some of these little creatures were above a thousand times smaller than the smallest ones which I have hitherto seen on the rind of cheese, wheaten flour, mold and the like . . . . Some of these are so exceedingly small that millions of millions might be contained in a single drop of water. I was much surprised at this wonderful spectacle, having never seen any living creature comparable to those for smallness; nor could I indeed imagine that nature had afforded instances of so exceedingly minute animal proportions.

His vocabulary must have seemed a bit undignified to the British scientists at times – describing the plaque between his teeth, he wrote,

I then most always saw, with great wonder, that in the said matter there were many 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.

But Antony’s intense curiosity and amazement at what he was seeing provided the energy and patience to hold his little two-inch microscopes, illuminated by a nearby candle-flame, up to his eyes repeatedly for five decades.

Of his motivation, he himself wrote, “…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.” Clifford Dobell, a translator of many of his letters, describes him thus:

“Our Leeuwenhoek was manifestly a man of great and singular candour, honesty, and sincerity.  He was religiously plain and straightforward in all he did, and therefore sometimes almost immodestly frank in describing his observations.  It never occurred to him that Truth could appear indecent.  His letters, accordingly, are full of outspoken thoughts which more ‘scientific’ writers would hesitate to put on paper: and to the modern reader this is, indeed, one of his particular charms–for he is far more childlike and innocent and ‘modern’ than any present-day writer.” (Dobell, p. 73).

Antony investigated almost anything and everything that could be held up to his lens, exemplifying technical skill, persistence, curiosity, insight and penchant for accuracy that would become a model for others working in experimental biology. He was the first to observe bacteria, rotifers and protists like Vorticella and Volvox. He observed blood cells and was the first to see the whiplike action of sperm cells. He also labored passionately to dispel myths. Working independently, untied to the common misconceptions by scientists of his day, he used good empirical methods to find the truth. One year, for instance, when people found objects that looked like burnt paper with mysterious writing on them and attributed them to messages from heaven, Antony proved they were merely dried sheets of algae. In his proof, he did a model forensic analysis, even reproducing the processes that led to the phenomenon. More importantly, Leeuwenhoek refuted the doctrine of spontaneous generation that was popular in his day, the idea that living things emerge spontaneously from inanimate matter–eels from dew, shellfish from sand, maggots from meat, and weevils from wheat. He observed the complete life cycle of ants, fleas, mussels, eels, and various insects, proving that all organisms had parents. It would take another 150 years for the false notion of spontaneous generation to be dealt its final death blow under Louis Pasteur (although a new form of the doctrine arose in the twentieth century, of necessity under Darwinian philosophy, under the name “chemical evolution”).

Antony van Leeuwenhoek became somewhat of a celebrity in his old age. Visitors to his little shop wanting to see microscopic wonders included Peter the Great, King James II, and Frederick II of Prussia. His relationship with the Royal Society also brought him into contact with other leading scientists of the day. He had no regard for fame or position, though, and would rebuff royalty if he was too busy, or if they had not made an appointment. Truly his passion was for the wonders of nature that God had allowed him to investigate. There are indications he was also interested in navigation, astronomy, mathematics, and other natural sciences. He said, “Man has always to be busy with his thoughts if anything is to be accomplished.”

It is difficult to find much detail about Leeuwenhoek’s church attendance or spiritual life in most biographical sources, which tend to focus on his experimental achievements, but it is clear that faith in God and a love for creation were the key influences behind his scientific work. He was born into the Dutch Reformed tradition, which had a high view of Scripture and salvation in Jesus Christ, and a firm doctrine of creation. Of his religion, Richard Westfall of Indiana University writes, “He was baptized and buried in Calvinist churches, and his second wife was the daughter of a Calvinist minister.” This tradition, furthermore, understood and encouraged man’s role in the investigation of God’s handiwork in nature.  Dr. Abraham Schierbeek, the Editor-in-Chief of the collected letters of Leeuwenhoek, explains that he was part of the ‘New Philosophy’ of scientists like Robert Boyle, who regarded the study of nature as “a work to the glory of God and the benefit of Man.” The newly-formed Royal Society was made up largely of Puritans with similar convictions, from which we can infer Leeuwenhoek shared with them a common bond of belief, since he took great pride in his relationship with the Royal Society, mentioning it on his title pages and even on his tombstone. Schierbeek observes, “His works are full of his admiration of creation and the Creator, a theme which is frequently found in writings of this period; in becoming better acquainted with creation, men wanted to get nearer the Creator, a conviction which is found among many of the early members of the Royal Society.” (Schierbeek, p. 200). Thus we see again that Christianity was the driving force during the rise of modern science.

Of Leeuwenhoek’s personal faith, Schierbeek says,

“To this we must add his deep religious assurance, his complete faith in the ‘All-wise Creator,’ a never-flagging admiration for the perfection of the most minute, hidden mysteries of the work of His hands and the conviction that his researches would surely help to make His Omnipotence more universally known. Without ever lapsing into high-flown phrases he repeatedly gave evidence of his religious faith:  ‘Let us lay the hand on our mouth, and reflect that the All-wise hath deemed this needful for the reproduction of all that hath received movement and growth, and so, the why and the wherefore we can but guess after.’” (Schierbeek, p. 31).

It is clear, too, from his stand against non-Christian superstitions such as the doctrine of spontaneous generation, that he held to a Biblical doctrine of creation. He believed it foolish to think his little “animalcules” could have formed by chance, and he worked diligently to prove that all things reproduce after their kind, as the book of Genesis teaches. For example, after working for weeks observing the propagation of insects, Leeuwenhoek stated confidently, “. . .  This must appear wonderful, and be a confirmation of the principle, that all living creatures deduce their origin from those which were formed at the Beginning.” (Schierbeek, p. 137). After another remarkable series of experiments on rotifers in 1702 he concluded:

The preceding kinds of experiments I have repeated many times with the same success, and in particular with some of the sediment which had been kept in my study for about five months. . . .  From all these observations, we discern most plainly the incomprehensible perfection, the exact order, and the inscrutable providential care with which the most wise Creator and Lord of the Universe had formed the bodies of these animalcules, which are so minute as to escape our sight, to the end that different species of them may be preserved in existence. And this most wonderful disposition of nature with regard to these animalcules for the preservation of their species; which at the same time strikes us with astonishment, must surely convince all of the absurdity of those old opinions, that living creatures can be produced from corruption of putrefaction. [Schierbeek, p. 171]

From Leeuwenhoek’s writings we frequently sense the awe and wonder that can only emanate from a man who has a joyful, personal relationship with God the Creator. Dan Graves, in Scientists of Faith (Kregel, 1996), writes, “He often referred with reverence to the wonders God designed in making creatures small and great. His virtues were perseverance, simplicity, and stubbornness. He loved truth above any theory, even his own.  He asked of his challengers only that they prove their points as he proved his.” Schierbeek says, “Leeuwenhoek was driven by a passionate desire to penetrate more deeply into the mysteries of creation. To him, as to many others of his time, a watch was a greater specimen of craftsmanship than a clock in a tower; this opinion is reflected in his biological views. The microscope gave him the opportunity to study and admire the small organisms, the ‘animalcules,’ and whenever he was able he expressed his admiration of the beautiful things he saw.” (Schierbeek, p. 196).

Leeuwenhoek died in 1723 shortly after dictating his latest observations to the Royal Society. Clearly his long and full life was filled with the enthusiasm of scientific inquiry. Microscopy has come a long way since then; scientists now use electron microscopes which, at 100,000x, are hundreds of times more powerful, investigating wonders even more amazing than those Leeuwenhoek saw: DNA, molecular motors, and the machinery of the cell. Additional methods are allowing scientists to reconstruct molecules at the scale of billionths of a meter. A vast horizon of creation under the microscope still remains largely unexplored.

Do you have the Leeuwenhoek spirit?  We hope his story will encourage others to see the scientific investigation of nature as a source of joy, and a means of glorifying God. Dan Graves said, “Antonie van Leeuwenhoek’s life glorified God in many ways, but perhaps most by showing us that there is far more under the sun than we had first suspected.”

Clifford Dobell, F R S, Protistologist to the Medical Research Council, London, Antony van Leeuwenhoek and His “Little Animals,” Staples Press Ltd (Cavendish Place, London, 1932), QH 31L55 D6.  This large book (435 pp.) contains new translations of many of Leeuwenhoek’s letters, but focuses on his observations.  The author gives excessive details about Leeuwenhoek’s name, city, portraits and other matters, but seems to de-emphasize references to his faith or spiritual life.

Dan Graves, Scientists of Faith, (Kregel Publications, 1996), ch. 17.

A. Schierbeek, PhD, Editor-in-Chief of the Collected Letters of A. v. Leeuwenhoek, Formerly Lecturer in the History of Biology in the University of Leyden, Measuring the Invisible World: The Life and Works of Antoni van Leeuwenhoek F R S, Abelard-Schuman (London and New York, 1959), QH 31 L55 S3, LC 59-13233 .  This book (223 pp.) contains excerpts of Leeuwenhoek’s letters and focuses on his priority in several new branches of science, but makes several important references to his spiritual life and motivation.