Visited by Holger Jacobæus, the Bartholin brothers, and Arent Seyn; described as "ingenious but illiterate"
Visited by three Danes -- Holger Jacobæus and the Bartholin brothers -- and their Dutch host and no doubt translator 
Arnold Sijen. They were accompanied by Thomas Bartholin's sons Christopher and Caspar 1655–1738. Three years after this visit, Caspar would be the first to describe what we now call Bartholin's gland.
- Holger Jacobæus, also Oliger Jacobi (1650-1701), physician and naturalist. He was professor of medicine, philosophy, history, and geography at University of Copenhagen.
- Thomas Bartholin (1616-1680) (right; click to enlarge), Danish physician, mathematician, and theologian. He is best known for his work in the discovery of the lymphatic system in humans.
- Rasmus Bartholin (1625-1698), Danish scientist, physician and grammarian. He wrote the first grammar of the Danish language.
- Arnold Sijen, also Arnoldus Syen, Arent Seyen, Seijen (1640-1678 in Leiden), professor of botany and, after 1670, supervisor of the herb garden at Leiden University. In a letter to Henry Oldenburg earlier that year, Constantijn Huygens made light of Syen's and Swammerdam's struggles using a microscope.
from Thomas Bartholin's Acta medica & philosophica Hafniensia, vol. III, 1677, p. 8
Writing in Latin, Caspar Bartholin described Leeuwenhoek as hominum ingeniosum, sed illitaratum, nomine Leuenhug, an ingenious but illiterate man, named Leuenhug. By illiterate, of course, he meant that Leeuwenhoek did not know Latin or have a university education. Caspar continued:
I saw different microscopes, that he had made himself and were so pure, that they had aroused admiration in everyone. Through them, I have ... seen the following:
1. Blood, enclosed in an elongated glass, consisting of small pure spheres that moved back and forth, and up and down, in all directions. And in addition, the serum was observed, floating in the blood.
2. Also hair, inside hollow, consisting of balls, to say nothing of stones, nails, skin, all kinds of wood; hairs drawn from the mustache of a cat had a cavity in cross section, like a cannon.
3. We also saw flies and bees and other small animals through the microscopes.
