Henry Oldenburg wrote to Leeuwenhoek about the reaction in London to his observations

January 7, 1676

When Oldenburg wrote this letter on December 28 in London, it was January 7 in Holland.

This letter is known only from Leeuwenhoek's reference to it at the beginning of his letter of 1676-01-22. Oldenburg must have written it in French, because Leeuwenhoek replied:

Your letter of the 28th was received by me in good order, from which I learned that you do not doubt my knowledge of French, but I must tell you that I regret I do not understand any language but Dutch and when you write to me in French or Latin I can help myself all right, since I have enough friends who will translate it for me; but I cannot help myself with the English language since the death of a certain gentleman who was proficient in this language.


The Correspondence of Henry Oldenburg vol. XII, p. 116