Lambert van Velthuysen

Other name: 
Veldhuizen, Veldhuyzen
correspondent who lived in Utrecht
Death or Burial date: 
November 5, 1685

wikipedia nl

Velthuysen (also spelled Veldhuizen, Veldhuyzen) was a well-educated member of the Utrecht city council and a magistrate there. He wrote, mostly in Latin under the name Velthusius, about philosophical and theological subjects. He was also a fervent advocate of Descartes' ideas. He corresponded with Spinoza.

Leeuwenhoek wrote four letters to Velthuysen in 1679, dated May 9, June 13, July 11, and November 14. They discussed Leeuwenhoek's observations of sperm and his ideas about reproduction.

According to Early Modern Letters Online, Velthuysen wrote a letter to Leeuwenhoek on 2 May 1694 sourced from the ePistolarium. I can't find it there.

Leeuwenhoek's Letter 45 of 11 May 1679, his first to Van Verthuysen, refers to "The very courteous and pleasant letter of Your Honour of the 12th of April," so Van Velthuysen must have initiated the correspondence.