#Global demographic transition windows

Though his tiny peephole gave him privileged access to a never-before-seen microscopic universe, he spent an enormous amount of time looking at spermatozoa, as they’re now called. Leeuwenhoek became a bit obsessed after that.

#Global demographic transition windows

One imagines sunlight falling through leaded windows on a face lost in contemplation, as in the Vermeers. “Sometimes more than a thousand,” he wrote, “in an amount of material the size of a grain of sand.” Pressing the glass to his eye like a jeweler, Leeuwenhoek watched his own animalcules swim about, lashing their long tails. Now he had something more delicate to report: Human semen contained animalcules too.

The learned men in London were still trying to verify Leeuwenhoek’s earlier claims that unseen “animalcules” lived by the millions in a single drop of lake water and even in French wine. Leeuwenhoek had made it himself nobody else had one so powerful. Its lens, no bigger than a small raindrop, magnified objects hundreds of times. “Before six beats of the pulse had intervened,” as he later wrote to the Royal Society of London, Leeuwenhoek was examining his perishable sample through a tiny magnifying glass. He’d had five children already by his first wife (though four had died in infancy), and fatherhood was not on his mind. Cloth was Leeuwenhoek’s business but microscopy his passion. One day in Delft, Dutch Republic, in the fall of 1677, Antoni van Leeuwenhoek, a cloth merchant who is said to have been the long-haired model for two paintings by Johannes Vermeer-“The Astronomer” and “The Geographer”-abruptly stopped what he was doing with his wife and rushed to his worktable. This story was published in the January 2011 issue of National Geographic magazine.