text: Eye of the Beholder . by Laura J Snyder . (Head of Zeus, £25) The behaviour of Dutch natural scientist Antoni van Leeuwenhoek was nothing if not eccentric. In 1677, at the age of 41, he embarked on an extraordinarily gruesome experiment, using his body as a guinea pig. Antoni van Leeuwenhoek (pictured in a portrait ) used his body as a guinea pig in an experiment . He took three lice, nestled them among the hairs of his calf, rolled up a tight stocking so that the insects were bound to his leg and then left the stocking on and did not bathe for six days. On the seventh day, he removed the stocking and counted more than 80 eggs but no young lice. In the interests of empiricism, the stocking went back on for another three days. Finally, the stocking came off to reveal at least 25 lice running up and down his leg. ‘This spectacle of all the young lice filled me with such aversion to the stocking,’ he wrote, ‘that I threw it, along with all the lice in it, out the window.’ He rubbed down his legs with ice, then took up his pen to calculate the louse’s reproduction rate. He estimated that two pairs of lice could generate 10,000 young in only eight weeks. While Leeuwenhoeck was thus engaged, another great Dutchman, Johannes Vermeer, was intent on his own more genteel studies in his house on the opposite side of Delft’s market square. Draped in a black cloth, Vermeer spent hours peering into the box-like interior of a camera obscura, an ancestor of the photographic camera. This was a light-tight wooden chamber with a hole or lens on one side, which could be used to project an image of a scene on to a glass plate or wall. They had been used for party tricks and for viewing solar eclipses but were increasingly being employed by artists to render paintings more lifelike than ever. The experiments of these two men are the subject of Laura J. Snyder’s new biography. She asks an intriguing question: could Vermeer and Leeuwenhoek, who were born in the same week, lived and worked their entire lives in an area not much larger than a football pitch, and who had friends in common, have exchanged ideas and inspired each other’s work? This is much more than a joint biography. It is a portrait of an age of insatiable intellectual curiosity. The 17th century gave us an inventory of instruments which far extended man’s understanding of the world: accurate thermometers and barometers, the air pump, the pendulum clock, improvements to the telescope, the refinement of the microscope. Leeuwenhoek’s mastery of lens-grinding saw him build a microscope capable of magnification up to 480 times. Scientists and dilettanti assembled cabinets of curiosity filled with rare animal and shell specimens. Leeuwenhoek’s collection included the eye of a whale, pickled in brandy. Anatomical theatres for the dissection of bodies were built in Padua, Bologna, Leiden, Delft and Amsterdam. According to one chronicler, sumptuously dressed ladies would attend dissections of the bodies of executed criminals and then go straight to that night’s ball. Snyder moves effortlessly not just between Vermeer’s studio and Leeuwenhoek’s laboratory, but all over Europe, from the universities of Italy, to the halls of the Royal Society in London, then the world’s pre-eminent scientific institution. Leeuwenhoeck wrote about 300 letters to the Royal Society, charting 50 years of experiments. He addressed them as ‘curious gentlemen dabblers’. One of his great discoveries was the observation of thousands of swimming creatures, which he called animaculae or little animals, in murky water. He estimated there could be more than eight million of them in a single drop. Later generations would recognise them as bacteria. He was also the first scientist to observe the existence and movement of sperm. No one had yet seen the human sperm or the egg or understood their part in reproduction. Leeuwenhoek politely wrote to the President of the Royal Society: ‘What I investigate is only what, without sinfully defiling myself, remains as a residue of conjugal coitus.’ One feels a certain amount of sympathy for his wife, Cornelia. What with the lice and the post-conjugal microscope experiments, she must have been a very patient woman. The great pleasure of this book is how Snyder makes the science clear to the layman. I have a degree in history of art and only one measly science GCSE in biology. Yet I was left more eager to peer down the lens at one of Leeuwenhoek’s slides, than to stand before even the most pellucid of Vermeer’s exquisite paintings.
target: At 41 van Leeuwenhoek used his body as a guinea pig in an experiment .
  Vermeer spent hours peering into the box-like interior of a camera obscura .
  Could Vermeer and van Leeuwenhoek have inspired each other’s work?