Cornelia Johannes Swalmius

Other name: 
Birth or Baptism date: 
April 9, 1634
Death or Burial date: 
January 6, 1694


Daughter of a Dutch Reformed clergyman, Cornelia grew up in Valkenburg, about 20 km (12 mi) north of Delft, near Leiden. When she was 36, she and Antony were married by Abraham Bredius in the church (right) in Pijnacker, a village two miles from Delft, where her uncle was sheriff. She died childless 23 years later and was buried near Barabara under the floor of the Oude Kerk.

Her death register has a remark, which is rare. After her husband's name, it says: "Anthonij is lid van de Koninklijke Cosieteit in Londen." Antony is a member of the Royal Society in London. This may have been Cornelia's crowning achievement.

Some biographers have assumed that her family's social circle brought Leeuwenhoek into contact with a group of university-educated professionals who may have encouraged his lens-grinding and careful observations. There is no documentary evidence to support this inference of causality. It could have been the other direction, that his increasing contact with university-educated professionals brought him into contact with Cornelia's family. They had both lived in Delft for the twenty years before their marriage and it is a small town, so it is equally plausible that they knew each other for years.

Regardless, Leeuwenhoek's scientific career began shortly after his marriage to Cornelia. He refers to her several times in letters (February 21, 1679 and September 17, 1683) as a source of specimens.

Leeuwenhoek sent a letter two weeks before her death and another two weeks after her death, both to the Royal Society, Alle de Brieven / Collected Letters numbers 131 and 132. Neither indicate anything amiss in his personal life.