This article argues that Library History ought to be guided by well-contextualized questions of cultural history. It proposes one such question: that which asks after the ways in which repositories of knowledge were created, organized and used in the past. The examples that are discussed in this article suggest that within the social context of the Republic of Letters an ideal of sharing knowledge was developed, which informed later, eighteenth-century, attempts at making repositories and libraries widely available. Modern ideals of collecting and sharing knowledge are not as new as they would appear to be. This is to say that the ideal of ‘Open Science’ has a history.