Digital edition of the Clusius correspondence

Johannes de Jonghe to Clusius, 1596. UBL Vul. 101.

The Clusius letters

The correspondence of Carolus Clusius comprises 1600 letters, of which some 1200 are kept in the University Library Leiden (facsimiles can be consulted on the website of the University Library Leiden). The letters are written by Clusius and a range of persons from all social layers with an interest in natural history, gardening, literature, travel, politics, religion and everyday life. Over the course of the last two centuries, these letters have gained considerable attention from historians and biologists, but a complete edition was never realized.

Online edition-in-progress

Huygens ING and the Scaliger Institute (Leiden University Libraries) made a big step towards a complete digital edition of the Clusius correspondence by assembling and digitizing all existing transcriptions of the letters in eLaborate (a collaborative transcription tool developed by Huygens ING). The first release of this ‘edition-in-progress’, under direction of dr. Esther van Gelder (Huygens ING), is now online and can be viewed at It includes metadata belonging to all known 1600 letters, scans of 1170 letters and transcriptions at different stages of completion of almost 1000 letters.

This web edition is not a scholarly edition in the traditional sense. Due to the many different sources of the (published and unpublished) transcriptions, the quality of the edition is not uniform. Furthermore, virtually no annotation has been added (yet). But by publishing this edition as a work-in-progress, we expect to offer an invaluable source that can be searched, improved and elaborated by everyone.

Search and collaborate

Researchers and students are invited to browse and search the  online edition and to join the project with new transcriptions, translations, improvements of existing transcriptions, annotations etc. Those interested are most welcome to join the Clusius Community 2.0 and to contribute to this edition! Contact us via