- de Meij
- de Molijn
- van den Berch
- Hogenhouck family
- Civic career
- Scientific career
- Delft in Holland
friend from the Stadhuis in the 1660's who went on to become Grand Pensionary of the Republic
November 23, 1641
August 3, 1720
Heinsius was a lawyer in Delft and member of the Veertigraad whose talents led him to become the city's pensionary (chief administrative officer). This early part of his life is discussed in detail in Het verstand komt met het ambt, referenced below.
The same year that Leeuwenhoek was appointed city inspector, 1679, Heinsius became pensionary for Delft in the States of Holland. In 1682 stadholder William III of Orange appointed Heinsius special negotiator to France. The mission was a failure but he made a favourable impression on William III.
Leeuwenhoek wrote six letters to Heinsius in 1683, when he beginning his political career outside Delft. He wrote two more in 1685.
Within a decade, Heinsius had become, somewhat reluctantly given the grisly history of the office, Grand Pensionary of the whole province of Holland. In that job until his death, he played a crucial role guiding the Republic and William III, prince of Orange, by then King of England, through wars with France and Spain. Leeuwenhoek wrote eight more letters to Heinsius at the end of the century.
A decade later, toward the end of the Nine Year's War against France, Leeuwenhoek again began addressing letters to Heinsius, by then one of the most powerful diplomats in Europe.
They are both buried in the Oude Kerk, and Leeuwenhoek undoubtedly attended the funeral of his old friend in 1720.