Dangerous Books – 500 Years of Science Under Fire
6 maart tot en met 30 augustus in Teylers Museum
Tuesday 17 February 2026
In the exhibition 'Dangerous Books – 500 Years of Science Under Fire' visitors can follow European and American histories of censorship by Church and State on the basis of (popular) scientific publications. After all, knowledge is power and that could pose a threat – some people in power still believe it does. 'Dangerous Books' will be on view from 6 March up to and including 30 August at Teylers Museum in Haarlem.
Denis Diderot & Jean le Rond d’Alembert, Encyclopédie, ou Dictionnaire raisonné des sciences, des arts et des métiers. Parijs: Briasson, David, Le Breton, etc. Neuchâtel: Faulche, 1751-1772.
Knowledge for all
One of Teylers Museum’s key pieces is the 1751 Encyclopédie by Denis Diderot and Jean le Rond d’Alembert. It is a collection of all knowledge that was available at that time. The book was already purchased in 1780, four years before the museum opened its doors. It showcases the ideas of the Enlightenment: armed with knowledge all people would be able to think for themselves, form their own opinions, and criticise those in power. Church and State considered this a threat.
Teylers’ historical library contains more ‘dangerous’ books like this, for instance the 1735 book Systema naturae by Linnaeus. Linnaeus classified plants on the basis of sexual characteristic and placed humans in the class of quadrupeds, alongside apes. Many people were shocked by these ‘heretical and immoral’ ideas. In his Histoire & Théorie de la Terre (1749), George-Louis Leclerc de Buffon wrote that the earth was 75,000 years old, much older than it said in the Bible. This led to book burnings and bans by the Church.
The most famous page from Copernicus’s (1472–1543) 'On the Revolutions of the Heavenly Spheres'. Neurenberg, 1543. Collection Tresoar.
Photography: Marieke Balk
The Index of Forbidden Books
The introduction of the printing press facilitated the rapid distribution of knowledge. In 1559, this prompted the Church to compile the Index Librorum Prohibitorum: a list of forbidden books. Many of the works featured in the exhibition were on this list, which was only abolished in 1966. One of the most famous examples is Copernicus' On the Revolutions of the Heavenly Spheres in which he, as early as 1543, stated that the earth revolved around the sun instead of the other way around. The exhibition presents the most heavily censured copy of this work, on loan from the Biblioteca Statale di Cremona (Italy). The chapter about the movements of the earth was completely deleted, while other fragments were also erased. On the other hand, a copy that was owned by the astronomer Gemma Frisius from Dokkum, on loan from the Frisian archive Tresoar, shows how he added his own extensive notes and ideas.
As long as Copernicus’ ideas were presented as a hypothetical theory, the Church tolerated the book. However, when Galileo started defending heliocentrism as a reality a century later, the pope demanded it was censored. Apart from Galileo's book, works by Protestant authors who were listed on the Index are also featured in the exhibition. And Darwin’s theory of evolution is obviously included as well.
Banned by the State
A notorious example of state-manipulated science is Lysenkoism, which denounced scientific ideas of biological heredity in the communist Soviet Union. The authorities determined what research was conducted, how it was funded, and which results were made public. This had a disastrous effect on agriculture and led to famine. Governments have also been keen to control themes that mainly concern women, such as sexuality, contraception, and abortion. And in Nazi Germany, Einstein’s theory of relativity was banned.
Science under fire
Featuring over twenty books, the exhibition shows that religious and political censorship have left their mark on history. Today, the academic world is deeply concerned about the increasing pressure put on the freedom of scientific research, for instance by the Trump administration in the United States. Dangerous Books therefore extends an invitation to reflect: How much scientific freedom do we actually have these days?
Dangerous Books will be on view in Teylers Museum’s Exhibition Gallery 2 from 6 March up to and including 30 August 2026. Various public activities are organised to accompany the exhibition, including lectures (in Dutch) by Trudy Dehue, Marjoleine Molenaar, and Maretta Johnson. From 6 March, you will also be able to listen to the Dutch-language podcast episode Gevaarlijke boeken. More information.
