Profession: microscopist

The cloth-merchant Leeuwenhoek found how to make tiny but much clearer lenses for microscopy than scientists like Hooke, and made many discoveries in microbiology and comparative anatomy. De Graaf wrote to Oldenburg describing his friend’s superior instruments; Oldenburg (the first of various Royal Society secretaries Leeuwenhoek corresponded with across 50 years) became something of a mentor. Leibniz, Boerhaave, Swammerdam, Huygens and Sloane visited; Boyle and Hooke were among other correspondents (he probably saw a copy of Hooke’s ‘Micrographia’ when visiting London). There is much speculation that he knew the painter Vermeer, born days apart in Delft, but no confirming evidence.