Gottfried Leibniz wrote Letter L-520 to Leeuwenhoek about sperm and encouraging young people and training students

August 5, 1715

Text of the letter is not yet available at the DBNL - De Digitale Bibliotheek voor de Nederlandse Letteren.

Leibniz's letter covered several topics. He discussed the different position about spermatozoids held by the Italian physician Antonio Vallisnieri, who thought that the animal was already in the egg. Leibniz, as he had written in his recent book Essais de Théodicée, shared Leeuwenhoek's opposing view.

Leibniz hoped that Leeuwenhoek would continue with the publication of his Send-Brieven.

He urged Leeuwenhoek to establish a school for young people to learn how to research with the microscope.

Finally, he asked Leeuwenhoek's opinion about a book by Nicolaas Hartsoeker, Conjectures Physiques.

On the same day, Leibniz wrote about Leeuwenhoek to Louis Bourguet, a proponent of Vallisnieri's ovulist views.


Sämtliche Schriften und Briefe, Transkriptionen des Briefwechsels 1715, Leibniz-Archiv Hannover, no. 270, p. 368.

In response to something Bourguet had written about Leeuwenhoek, Leibniz wrote:

I would not wish to speak as decisively as you do, Sir, when saying that Mr Leeuwenhoek's view is a fable of extravagant proportions.

Bourguet replied from Venice later in August:

I am very obliged to you, Sir, for what you have deigned to tell me in favour of Mr Leeuwenhoek, whom I respect greatly. Besides, I by no means intended to offend him when I treated his opinion on spermatic worms as a hollow story. Nevertheless, I am not persuaded by his hypothesis. If I could have easily enclosed my proofs for the propositions I have the honour of sending to you, you would have found in abbreviated form the answer to the objections you have deigned to make to me.