Hidden Worlds Under the Microscope

Lenses that revealed the very small opened a world no one had suspected. In 1665 Robert Hooke published Micrographia, a bestselling book of detailed engravings of fleas, mould and cork; looking at cork, he used the word 'cells' for the tiny compartments he saw. In the Dutch city of Delft, the cloth merchant Antonie van Leeuwenhoek ground tiny single lenses that magnified more than 200 times.

From the 1670s he sent letters to the Royal Society describing 'animalcules', living microorganisms in pond water and in scrapings from teeth. Many scholars were initially sceptical, and the Society had witnesses confirm his reports. The microscope showed that life was far more varied than anyone imagined, but its medical importance was not understood for nearly two centuries, until germ theory linked microbes to disease. Its history shows that seeing something is not the same as understanding what it means.