Universiteit Leiden

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Bibliotheca Thysiana

Dissertation on the life and library of Johannes Thysius

Johannes Thysius, a 17th-century inhabitant of Leiden, left behind the Thysiana Library, the Netherlands' first private library to be open to the public. PhD candidate Esther Mourits reconstructed how Thysius built up his collection and why he opened it to the public. PhD defence 14 December.


On the corner of the Rapenburg and the Groenhazengracht in Leiden is the first library building in the Netherlands, constructed in 1655 specially for this purpose. The well-to-do Johannes Thysius (1622-1653) died at the very early age of 31. In his will he stated that his collection of around 2,500 books and a large number of pamphlets should be used 'for the public service of study'. This was an exceptional decision for the time: no other instance is known from the Republic. 

The library at Rapenburg 25

Versatile collection

This is the first time that in-depth research has been done on Thysius' life and collection. A number of articles have been written about the book and print collection, but two principal questions have so far remained unanswered; how did the library come about, and why?  

Personal archive

Mourits delved into Thysius' archive and read all his letters that have been preserved - 300 that he himself sent and 380 that he received. Remarkably, there is less evidence in the letters of Thysiuis' love of books than one might expect. In his correspondence there are just three references to his interest in books and libraries. In one instance he wrote to a friend that there is no greater pleasure than spending time in a library. Mourits also found a letter about a visit by German Johann Ernst Gerhard, a contemporary of Thysius from Jena, who made his extensive library available for study. Mourits believes that Thysius must have been inspired by examples such as these.  

Two uncles were professors

His family also played an important role in his passion for collecting. His uncles, both professors of theology at Leiden University, gave him 300 books when he was just 13 years old. These two uncles were guardians to Thysius, whose parents died at a relatively young age.  

Johannes Thysius. Photo: Biblioteca Thysiana

Susceptible to status

Thysius' cash books show that he spent a lot  of money on luxury items, such as expensive clothes and horses, and that he always had a servant with him. He was susceptible to status, Mourits concludes. He liked books, but collected them probably because they gave him some prestige, particularly in a university city like Leiden. His books bear no signs of use, such as notes in the margin. ‘You think you're dealing with a scholar, but I found no trace of any research carried out by him. He studied law, but that didn't lead to an academic career.'

Rare data about origin and prizes

Besides Thysius' personal history, the research also provided new insights on the collection, such as the provenance of some of the books. Thysius wrote in the margin of his cash book the names of the auctions where he bought his books.  He also recorded what he had paid for each book. 'This level of detail tells us about the market value of the books at that point in time. These are very rare data.' 

Thysius collected books on the most diverse subjects, such as Arabic sayings, philosophy, magnetism, insects, marine navigation and planets, as well as about Italian cuisine.  Photo: Bibliotheca Thysiana

Neglect helped preserve library

The Thysiana Library was a centre of knowledge and study in Leiden for a long time, but all that changed within a couple of generations. In his will, Thysius had stated that the library must remain under the guardianship of two curators, preferably members ofhis own family. But these curators failed to do their work properly: within a very short time, no further additions were made to the library. After the last curator committed suicide in 1768, following a life plagued by debt, the university took over the curatorship. Mourits: ‘It is partly because of this neglect on the part of his family that the monument has been so well preserved and that is remains to this day a true 17th-century library.' 

A commercial edition of the dissertation Een kamer gevuld met de mooiste boeken has been published by Vantilt. 

The Thysiana Library is owned by a foundation, and is managed by Leiden University. The books cannot be read in the library itself, but can be ordered via the University Library for viewing. Visits to the Bibliotheca Thysiana are by appointment.

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