The Royal Society published Leeuwenhoek's letter of October 9, 1676, reporting microbes in infusions

March 25, 1677

A long extract from the letter written on October 9, 1676, reporting observations of microbes in spice infusions, was published in Philosophical Transactions, volume 12. Oldenburg translated it himself, but included less than half of the original. In retrospect, we see this as Leeuwenhoek's most important publication because it introduced us to the microscopic world.