Grotius left a great number of autograph documents. Of these, Leiden University Libraries possesses eight manuscripts and a few hundred letters. Among the manuscripts, De Iure Praedae (BPL 917; On the Law of Prize and Booty) is considered the most important. It examines the historical, political, and legal aspects of war, and stresses the freedom to navigate the seas. It was written by Grotius between 1604 and 1608, but was never published in its entirety.
|Only the twelfth chapter appeared in print in 1609, titled Mare liberum. The manuscript clearly shows a work in progress as Grotius crossed out large parts of the text and made numerous alterations and additions. In 2015 the manuscript was subject of an extensive conservation treatment in order to be scanned for a digital edition, showcasing all of Grotius’ notes and changes.|