Secrets to light - National Library digitises its collection of clandestine literature

Date published

Also known as the "Atheist’s Bible", the Traitè de trois imposteurs is found in the collection under the title La vie l’esprit de Mr. Benoit de Spinoza.

Picture by
Kansalliskirjasto / Marko Oja

The National Library’s collections include 55 manuscripts of secret, underground philosophical literature from the 17th and 18th centuries. Now, this collection of clandestine manuscripts has been digitised and published for free use in the service.

The word clandestine is borrowed from French and means something that is secret, concealed and illicit. Clandestine literature refers to illicit, “underground” philosophical literature which, because of its content, was not authorised to be printed in Europe in the 17th and 18th centuries. In this context, philosophical refers most of all to heterodox literature against religion and the church as well as to works critical of the dominant social order, monarchy. As a result, such works were circulated among the learned as manuscripts that were copied and distributed under the counter in bookstores and from hand to hand.

In 1833, the University of Helsinki, then known as the Imperial Alexander University, received a substantial donation of books from St. Petersburg to replace collections destroyed in the Great Fire of Turku. The core of the donation consisted of the library of Russian diplomat Johann Albrecht von Korff (1697-1766), which had been purchased by Catherine the Great. The library reflects von Korff’s book-loving and eccentric nature and includes, among other works, 55 titles of clandestine philosophical literature in French, German and Latin. 

The handwritten manuscripts could not be digitised using the National Library’s normal optical character recognition (OCR) process and are only available as scanned images for the time being. The National Library has plans for a future project that would attempt to transcribe the manuscripts using the Transkribus platform for handwritten texts, while testing the method’s suitability for the Library’s digitisation process.

Currently, a total of 384 manuscripts categorised as clandestine literature are stored in the collections of European libraries, most of them in France. As such, the National Library’s collection of 55 titles is exceptional, and publishing it online is a culturally significant act on the global scale. The National Library’s digitisation process was made possible by a private donor.

Chief Information Specialist Mika Hakkarainen will give a detailed presentation of the manuscripts at the Mikkeli Science Forum on 14 April. The programme for the public and free online event can be found at

The digitised works are freely available in the service at

For further information, please contact:
Mika Hakkarainen, Chief Information Specialist
+358 2941 40950