The term the Republic of Letters is one that one can often encounter in the history of Early Modern or Modern Europe, but what does it mean and to whom does it apply? Republic comes from the Latin res publica and means res “affair, matter, thing” publica “public, people.” However, here it is the “people” or “men”, as they mostly were, of letters. So, our Republic of Letters is the affairs of the men of letters or literati, as they are today more often known. Most often the Republic of Letters is used, as for example on Wikipedia, to refer to the long-distance intellectual community in the late 17th and 18th centuries in Europe and the Americas. However, the earliest known appearance of the term in Latin, respublica literaria, appeared in a letter from the Italian politician, diplomat, and humanist Francesco Barbaro (1390–1454)
written to his fellow country man the scholar and humanist Poggio Bracciollini (1380–1459)
in 1417, so the original Republic of Letters was the Renaissance literary humanist movement of Northern Italy. Here, we also have a second interpretation of the Letters part of the term, meaning literally the letters that the members of the community wrote to each other to communicate their ideas, to announce their discoveries and to comment on the ideas and discoveries of others. In fact, that first use of the term came about when Poggio was off searching through monastery libraries and sent news of one of his discoveries back to Florence. Barbaro replied to his news thanking him for the gift offered to the literaria res publica for the greater progress of humanity and culture.
Initially this community of communication by letter was restricted to the comparatively small group of the literary humanists of Northern Italy, but with time came to embrace an ever-widening community from China to the Americas and including, as we will see, the whole world of science. Such a community didn’t exist in the Middle Ages, so what changed in the Renaissance that made this happen or indeed possible?
One simple, partial answer was the change of available writing material, when paper replaced parchment and velum. Parchment and velum were much too expensive to be used for large scale letter writing and correspondence. As I sit at my desk writing this post I’m surrounded by an abundance of paper, piles of books printed on paper, delivery notes, invoices and bank statements printed on paper, notebooks and note slips made of paper, a printer/scanner/copier filled with paper waiting to be printed and other bits and bobs made of paper. Paper is ubiquitous in our lives, and we seldom think about its history.
If we ignore the fact that wasps were making paper millions of years before humans emerged on the Earth, then paper has only existed for about 0.1% (approximately two thousand years) of the approximately two million years that the genus Homo has been around. It has only been present in Europe for about half of that time. Invented in China sometime before the second century BCE,
paper making was transmitted into the Islamic Empire sometime in the eighth century CE. It first appeared in Europe in Spain in the eleventh century CE. This is of course during the High Middle Ages but the knowledge and use of paper remained restricted to Spain, Italy, and Southern France until well into the fourteenth century, when paper making began to slowly spread into Northern France, The Netherlands, and Germany. The first English paper mill wasn’t built until 1588.
New production technics and new raw materials for paper production vastly increased output and reduced costs, so that by the fifteenth century paper was much more widely available and by many factors cheaper than parchment and a growing letter writing culture could and did develop. However, before that culture could truly develop, another aspect that we take for granted had to be developed, a delivery system.
Once again, as I sit in front of my computer, I can communicate almost instantly with people all over the world by email or at least a dozen different social media channels. I can also grab my mobile telephone and either telephone with it or send an SMS. Or I can phone them with my landline telephone and if I want to send something tangible, I can resort to the post service or anyone of a dozen international delivery companies. We live in a thoroughly network society. Most of this simply didn’t exist forty years ago but even then, the landline telephones and the postal services connected people worldwide if at much higher costs. Of course, none of this existed in the Middle Ages.
In the High Middle Ages only the rulers and the Church had courier services to deliver their missives, others were dependent on the infrequent long distant traders and travellers. This began to change in the late Middle Ages/Renaissance as long distant trade began to become more and more frequent and the large North Italian and Southern German finance house became established. Traders and financiers built up communications networks throughout Europe, which also functioned as commercial post services. Big trading centres such as Nürnberg, Venice, and the North German Hansa cities had their own major, highly efficient courier services.
Late in the fourteenth century the Dutchy of Milan set up a postal service and in the second half of the fifteenth century Louis XI set up a post service in France. In 1490 the Holy Roman Emperor Maximilian I gave the von Taxis family a licence to set up a postal service for the whole of the empire. This is claimed to be the start of the modern postal series.
By fifteen hundred it was possible for scholars throughout Europe to communicate with each other by letter and they did so in increasing numbers, setting up their own informal networks of those interested in a given academic discipline: Natural historians communicated with natural historians, mathematici with mathematici, humanist with humanists and not least artists with artists.
With the advent of the of the so-called age of discovery the whole thing took on a new dimension with missionaries and scholars exchanging information with their colleagues at home in Europe from the Americas, Africa, India, China, and other Asian lands. Here it was the big international trading companies such as the Dutch East India Company and English East India Company, who served as the courier service.
There is another important aspect to this rising exchange of letters between scholars and that is the open letter meant for sharing. This was an age when the academic journal still didn’t exist, so if a scholar wished to announce a new discovery, theory, speculation, or whatever he could only do so by word of mouth or by letter if what he wished to covey was not far enough developed or extensive enough for a book or even a booklet. A scholar would write his thoughts in a long letter to another scholar in his field. If the recipient thought that the contained news was interesting or important enough, he would copy it and send it on to another scholar in the field or even sometimes several others.
Through this process ideas gradually spread through a chain of letters within an informal network, throughout Europe. By the seventeenth century several significant figures became living post offices each at the centre of a network of correspondence in their respective field. I recently wrote about Marin Mersenne (1588–1648), the Minim friar, who served such a function and who left behind about six hundred such letters from seventy-nine different scientific correspondence in his cell when he died.
His younger contemporary the Jesuit professor of mathematics at the Collegio Romano, Athanasius Kircher (1602–1680), sat at the centre of a world spanning network of some seven hundred and sixty correspondents, collecting information from Jesuit missionaries throughout the world and redirecting it to other, not just Jesuit, scholars throughout Europe.
One of his European correspondents, for example, was Leibniz (1646–1716), who himself maintained a network of about four hundred correspondents.
Two members of Mersenne network, who had extensive correspondence networks of their own were Ismaël Boulliau (1605–1694), of whose correspondence, about five thousand letters written by correspondents from all over Europe and the Near East still exist although many of his letters are known to have been lost
and Nicolas-Claude Fabri de Peiresc (1580–1637), who certainly holds the record with ten thousand surviving letters covering a wide range of scientific, philosophical, and artistic topics.
Later in the century the European mathematical community was served by the very active English mathematics groupie John Collins (1626–1683), collecting and distributing mathematics news. His activities would contribute to the calculus priority dispute and accusations of plagiarism between Newton and Leibniz, he, having supposedly shown Newton’s unpublished work to Leibniz. Another active in England at the same time as Collins was the German, Henry Oldenburg (c. 1618–1677), who maintained a vast network of correspondents throughout Europe.
Oldenburg became Secretary of the newly founded Royal Society and used his letters to found the society’s journal, one of the first scientific journals, the Philosophical Transactions, the early issues consisting of collections of the letters he had received. Oldenburg’s large number of foreign correspondents attracted the attention of the authorities, and he was for a time arrested and held prisoner in the Tower of London on suspicion of being a spy.
The simple letter, written on comparatively cheap paper and delivered by increasingly reliable private and state postal services, made it possible for scholars throughout Europe to communicate and cooperate with each other, starting in the Early Modern period, in a way and on a level that had not been possible for their medieval predecessors. In future episodes of this series, we will look at how these correspondence networks helped to further the development of various fields of study during the Renaissance.
The Renaissance Mathematicus 
Of course, there was a secret reason behind rulers setting up postal services, and that was it gave them access to the communications travelling through their kingdoms. As long as the messages were transmitted using couriers it was difficult to do so (essentially they had to corrupt the courier). With state postal services they had access to the letters directly and this led to the rise of the ‘black chambers’ from 1500 onwards and the orgins of cryptanalysis.