How did Leeuwenhoek send and receive letters?

Europe's international postal systems changed during Leeuwenhoek's lifetime, as did the system within the Dutch Republic.

Before the 17th century, both secular and religious governments had systems to carry messages between royal courts and between monasteries. Since literacy wasn't widespread outside those locations, private messaging was done ad hoc either by giving a message to someone or by hiring someone to take it. In Europe, the Tassis family (later using the name Thurn und Taxis) developed an international network throughout the Holy Roman Empire. Brussels was one of the major hubs. After 1506, the system was opened to use by private individuals.

Before the end of the Eighty Years' War, Brussels was part of the Spanish enemy's empire. It wasn't until 1648 that the Dutch were able to establish a republic-wide system. The regular boat traffic on the major canals connecting the cities made the Dutch system the most efficient inter-city system in Europe.

Within each city in the Republic, economic prosperity developed hand-in-hand with reliable written communication. Harold Cook's Matters of Exchange develops that idea in detail. Cook argues that reliable written communication also enabled the rise of what we now call science. Remember that Leeuwenhoek wrote only letters, and that his two major means of communicating with the world depended on postal services.

  • Philosophical Transactions was distributed via the postal services.
  • People rountinely copied Leeuwenhoek's letters and articles by hand and sent them to others via the postal services.

Even at the time, those involved referred to the Republic of Letters as a supra-nation that resulted from efficient postal services, reliable and speedy. It let Leeuwenhoek stay in Delft, arguably the center of the civilized world at the time, and receive information from all over Europe.

Postal carrier on horseback with horn, 1668.

After 1648, messengers on horseback could more safely carry their letters and parcels along fixed routes at fixed times. Given the decentralized nature of power in the Republic, it is not surprising that each city had its own system. In Delft, the city government had messengers (boden) to carry information to the people and from them back to the officials in the Stadhuis as well as a traveling messenger to other cities.

For mail between individuals, Delft had two messenger services by the 1670's, when Leeuwenhoek became active. In the summer of 1678, the mayors combined the two under the management of Lambert Twent. After that, Leeuwenhoek would have used Twent's service.

How did Leeuwenhoek's letters get to England? After 1668, they went by barge to either Maassluis (more directly) or Rotterdam and from there to den Briel and on to Hellevoetsluis. Boats carrying mail and later passengers went daily between Hellevoetsluis and Harwich in England. From there, the mail went by coach to London. One way, it took four days and later three days to for the letters to make the trip. Letters going in the other direction, to Leeuwenhoek, were supposed to go via Amsterdam, which held monopoly rights. However, disputes, especially between Amsterdam and the up-and-coming Rotterdam, let the letters and copies of Philosophical Transactions reach Delft more directly.