Darwin’s personal scientific library, the majority of which is held at Cambridge University Library, has been digitised in a collaborative effort involving Cambridge, the Darwin Manuscripts Project at the American Museum of Natural History, the Natural History Museum, and the Biodiversity Heritage Library.

In total, Darwin’s library amounted to 1480 books, of which 730 contain abundant research notes in their margins. These annotated books are now in the process of being digitized. The first phase of this project has just been completed, with 330 of the most heavily annotated books launched online at the Biodiversity Heritage Library for all to read (http://www.biodiversitylibrary.org/collection/darwinlibrary).

University Librarian Anne Jarvis said: “The Darwin collections are among the most important and popular held within Cambridge University Library. While there has been much focus on his manuscripts and correspondence, his library hasn’t always received the attention it deserves – for it is as he engaged with the ideas and theories of others that his own thinking evolved.”

Because Darwin’s evolutionary theory covered so many aspects of nature, reading served him as a primary source of evidence and ideas. Darwin once complained that he had become a ‘machine for grinding general laws out of large collections of facts’.

The pages of Darwin’s Library, smothered as they are in his tantalizing scrawl, give us a direct view of the great Darwinian intellectual machine in action. With the Charles Darwin Library online, now everyone can retrace how Darwin systematically used reading to advance his science.

Most of Darwin’s personal library rests at Cambridge University Library and at Down House. Although the majority of the books are scientific, some are humanities texts on subjects that Darwin transformed into scientific topics.

The series of transcriptions accompanying each page allows everyone to see which passages Darwin found relevant to his work, stimulated his thinking, or just annoyed him as he read the work of others.

For example, his friend Charles Lyell wrote in his famous Principles of Geology that there were definite limits to the variation of species. Darwin wrote alongside this: “If this were true adios theory” (see above image).

The online transcribed marginalia relies on the work of two scholars, Mario A. Di Gregorio and Nick Gill, published in the 1990s and now greatly enhanced by Gill. Finally, in addition to images of the books and transcribed jots, the information is fully indexed so that people can search for topics and ideas relevant to their interests or work.

The digitisation project was jointly sponsored by the JISC (Joint Information Systems Committee) and National Endowment of the Humanities through a Transatlantic Digitization Collaboration Grant.