Antonie van Leeuwenhoek

Antonie van Leeuwenhoek (1632–1723), a draper and chamberlain of the city hall in Delft, began grinding tiny glass bead lenses to inspect thread counts in linen fabrics. Without academic training, his extraordinary artisanal patience allowed him to craft handheld microscopes magnifying up to 300 times with astonishing optical clarity.

Peering into drops of pond water, dental scrapings, and blood, Leeuwenhoek was the first human being to see bacteria, protozoa (which he christened *animalcules*), spermatozoa, and capillary blood circulation. Over fifty years, he dispatched hundreds of letters in vernacular Dutch to the Royal Society of London, opening the microscopic realm to humanity.