Bestselling author Dan Brown, best known for the Da Vinci Code, has donated €300,000 to a Dutch book collection focusing on esoteric works dating back centuries.

The Bibliotheca Filosofica Hermetica collection includes some 25,000 books covering 5,000 years of western spirituality and was put together by businessman Joost Ritman.

The money will be used to help pay towards digitalising the collection, which includes very rare volumes on alchemy and medieval religious movements as well as works by Spinoza and Comenius.

‘It was a wonderful surprise,’ library director Esther Ritman told the Volkskrant. ‘Dan Brown is a friend of the library and we know him well because he often does research here.’

Brown said in a video statement on the library website he considered it ‘a great honour to play a role in this important preservation initiative that will make these texts available to the public.’

The Dutch Prins Bernhard Cultuurfonds is also contributing €15,000 to the digitisation project. Ritman said the aim is to complete the process by next year and then the collection will be available online.