1685: Being ignorant of all other men's thoughts

1685 - "Being ignorant of all other men's thoughts, he is wholly trusting to his own"

In early 1685, Thomas Molyneux visited Leeuwenhoek at his home in Delft. A student at the university in Leiden, Monyneux was the 24-year-old brother of Royal Society fellow and Halley ally William Molyneux. The young man reported back to the Royal Society about Leeuwenhoek:

His only secret I believe is in making clearer glasses, and giving them a better polish than others can do.

I found him a very civil complaisant man, and doubtless of great natural abilities; but, contrary to my expectations, quite a stranger to letters, master neither of Latin, French or English, or any other of the modern tongues besides his own, which is a great hindrance to him in his reasonings upon his observations; for being ignorant of all other men's thoughts, he is wholly trusting to his own, which, I observe, now and then lead him into extravagances and suggest very odd accounts of things, nay, sometimes such as are wholly irreconcilable with all truth.

No doubt Leeuwenhoek had a different impression of such a visit from a representative of the Halley camp of mathematics-oriented researchers, a young man half his age who presumably spoke less Dutch than van Leeuwenhoek spoke English. While there is no record of Leeuwenhoek's side of the story, Molyneux also reported:

Such were the microscopes, which I saw, and these are they he shews to the curious that come and visit him; but besides these he told me he had another sort, which no man living had looked through setting aside himself; these he reserves for his own private observations wholly, and he assur'd me they performed far beyond any that he had shewed me yet; but would not allow me a sight of them.

Read the complete report. It is from such reports that Leeuwenhoek got the reputation for being secretive and amateurish. Perhaps he just lacked patience with snippy young foreigners.

And what happened next? Molyneux' letter was read to the Royal Society in early 1685. After that, there would not be another letter by Leeuwenhoek published in Philosophical Transactions until early 1693.

On 20 July he sailed from Billingsgate to Rotterdam, visited Amsterdam, Haarlem, and Utrecht, and finally entered at the university of Leyden. While there next year he met Locke, who afterwards wrote a letter to him from Utrecht on 22 Dec. 1684, thanking him for his kindness. In the 'Philosophical Transactions,' No. 168, he published an essay on a human frontal bone  in the museum at Leyden, of extreme size and thickness, an example either of Parrot's disease or of the osteitis deformans of Paget. On 14 March 1685 he made a report to the Royal Society on the collections of Swammerdam and Hermann, and in the same year went to Paris, where he stayed till his return to London in March 1686.


  • the three letters of January 5 and 23, 1685 (AB 82, 83), and March 30, 1685 (AB 84) were addressed to the members of the Royal Society. William Musgrave published them in volume 15 of 1685.
  • the next two -- July 13, 1685 (AB 85) and October 12, 1685 (AB 88), also addressed to member of the Royal Society, were published by Richard Waller in volume 17 of 1693. (See Period 5.)

Two to Heinsius in August and September

The situation was such at the Royal Society that both secretaries, Aston and Hooke, resigned on December 9, 1685. They were replaced a week later by John Hoskins and Thomas Gale. Seven years were to pass before Leeuwenhoek would have another letter excerpted in Philosophical Transactions.