Hendrik van Bleyswijk wrote to Gottfried Leibniz about encouraging Leeuwenhoek to take on students and teach them his "secret methods"

February 17, 1698

In this reply to Leibniz, Van Bleyswijk continued their discussion of encouraging Leeuwenhoek to take on students.

There is no record that Leibniz made a trip to Holland in those years or that Leeuwenhoek ever explained his “secret method” in writing.


Allgemeiner Politischer und Historischer Briefwechsel (General political and historical correspondence), vol. 15, January-September 1698, no. 223

I learned with great joy from the last letter, that you have done me the honor of writing it to me, that you intend to take a tour of Holland and the Netherlands, ... as also to lead you to our Monsignor Leeuwenhouck, to whom I communicated your letter, with which he was very happy, and particularly satisfied with the boxes you have the goodness to give him, but for what concerns your exhortation, to take some students, to teach them his secret method of observing, I also added mine to it, he still could not bring himself to do that, and all that I could get from him was that he would leave this method in writing, so that posterity will be able to use it.