What do you do?

What do you do when you see things that no one has ever seen before?

When you show these things to the people around you, they don't see them. Or they can't see or won't see them.

So then what do you do?

This web explores how a curious, methodical Dutchman responded to just that situation more than three hundred years ago.

17th century tile
made in Delft

Below is a silver magnifying glass aka microscope made by hand by Antony van Leeuwenhoek in the late 1600's (click to enlarge). The plate is less than 50 mm (2 in) high. It will fit easily into the palm of your hand. The single glass lens, almost spherical, is a little more than a millimeter (4/100th's of an inch) in diameter.

This microscope was an order of magnitude better in terms of magnification and resolution than any of the compound microscopes available in the mid-1600's.

What else is here?

Site Guide

How to use Lens on Leeuwenhoek. Abbreviations, spelling, and other trade-offs and compromises to adapt Leeuwenhoek's messy life to the rigors of the database.


Lists of primary sources in manuscript and print as well as secondary literature and tools for researchers into Leeuwenhoek's life and times.


Find information by search term.


Learning the Dutch language, with an emphasis on the 17th century.


Who made this web? Why? How? What about copyrights?

Featured page

When Leeuwenhoek's daughter Maria died, she left behind:

* more than ten thousand guilders in cash

* 70 bonds and other financial instruments paying her over three thousand guilders per year

* almost two thousand tea cups

* dozens of her father's instruments and tools

Learn more about The estate of Maria van Leeuwenhoek.