How we see the world today owes much to two 17th-century greats (Image: Ned M. Siedler/National Geographic Creative)
IN THE spring of 1694, the Royal Society of London received a letter from Antoni van Leeuwenhoek describing an experiment. Dissecting the eye of a dragonfly and pinning the cornea in front of a powerful lens, van Leeuwenhoek looked out on his street and spied the church steeple multiplied myriad times.
Van Leeuwenhoek was no stranger to the Royal Society. From his home in Delft, the self-taught scientist had dispatched regular accounts of his optical experiments since 1673, when he carried out the first observations of microbes through a home-made microscope.
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From dental plaque to blood cells to sperm, nothing was off-limits. Yet what most interested van Leeuwenhoek, says Laura J. Snyder in Eye of the Beholder, was 鈥渧isual perception itself鈥�. As it happens, van Leeuwenhoek had a neighbour with similar interests in visual perception and optics. Living just across Delft鈥檚 Market Square was the artist Johannes Vermeer, who used observation through lenses to craft his paintings.
There鈥檚 no evidence that the two knew each other, but physical proximity and many common friends make them irresistible subjects for a joint biography. Snyder makes spectacular use of this historical coincidence. As in her previous masterwork, The Philosophical Breakfast Club, she ingeniously explores the minutiae of her subjects鈥� lives to reveal sweeping changes in how their world was understood 鈥� ones that still resonate today.
When Vermeer and van Leeuwenhoek were born, just a week apart, in 1632, Delft was renowned for the quality of its lens glass. Although lenses were mainly used in eyeglasses, they were increasingly being incorporated into tools for scientists and artists. The telescope was invented around 1600; within a decade it had been transformed into a scientific instrument by Galileo, who also developed some of the earliest microscopes by adapting telescopes to study insects.
For artists in the 17th century, composition was frequently augmented by concave lenses, which condensed imagery for easier observation, and by convex lenses, which projected scenery on to canvas for more realistic perspectives. That set-up, also used by scientists to observe eclipses, was known as a camera obscura.
According to Snyder, Vermeer avidly experimented with all these aids, exploring 鈥渢he way the world appears to us through lenses as a way of understanding visual perception鈥�. Initially his focus was on simple optical effects, such as the way that a concave lens distorts proportions.
Artificial eyes
Although there鈥檚 no direct evidence that Vermeer used the camera obscura, Snyder speculates that he began to do so in the early 1660s, and was exhilarated by it. She bases her argument 鈥� convincingly 鈥� on close visual analysis of his paintings. Moreover, she attributes many of his works鈥� inventive qualities to his experience with it.
One example is the way Vermeer represented shadows. Hues hidden from sight in the darkness of a room become visible when projected on to a screen. By following what the camera obscura showed, Vermeer was able to increase the realism of his work.
Vermeer 鈥渦sed the camera obscura鈥� to experiment with light, to investigate and discover its optical properties鈥�, Snyder writes, deftly aligning the artist with his Delft neighbour. 鈥淏oth鈥� were employing optical instruments as 鈥榓rtificial eyes鈥� to supplement the natural organs.鈥�
Van Leeuwenhoek鈥檚 mastery of lens-making and microscopy are as extraordinary in their own way as Vermeer鈥檚 mastery of painting. Developing his own, mostly secret techniques, he built some 500 single-lens microscopes capable of magnifying objects as much as 450-fold, and performed micro-dissections that would be challenging even today. Nobody approached his technical capability, let alone patience. But as Snyder points out, his greatest achievement was interpretive.
Biology in the 17th century was totally unprepared for the sight of microbes, or even the tails on sperm. To make these discoveries, van Leeuwenhoek 鈥渘eeded to train himself to see what was there, not what he expected to find鈥�, Snyder writes.
聯Van Leeuwenhoek needed to train himself to see what was there, not what he expected to find聰
And that required a critical understanding of perception: like seeing the colour in shadows, seeing the tails on sperm required insight into sight, an awareness that observation isn鈥檛 passive.
Snyder sometimes overreaches in her effort to fit this notion to van Leeuwenhoek鈥檚 every dissection and Vermeer鈥檚 every brushstroke. But that doesn鈥檛 diminish her larger argument that active observation fundamentally changed art and science in the 17th century, and is 鈥渢he most radical influence of the seventeenth century on our time鈥�.
How radical? Snyder only hints at the reverberations, mentioning the vast amount of interpretation needed to 鈥渟ee鈥� what our new radio telescopes and electron microscopes can reveal about the unknown universe.
While she doesn鈥檛 discuss how data analysis and visualisation may be distorted by our preconceived ideas, there is clearly much we can learn from Vermeer and van Leeuwenhoek. Observing how they observed, we are primed to scrutinise our own beliefs.
Leader: 鈥�Who said the camera never lies?鈥�
This article appeared in print under the headline 鈥淭hrough a glass, clearly鈥�
