libraries were open to the public. Librarians were needed to plan and organize libraries to meet public needs. A tool to achieve these organizational goals, the first library catalog, appeared in 1595. Enlightenment era During the 16th century, the idea of creating a Bibliotheca Universalis, a universal listing of all printed books, emerged from well-established academics and librarians: Conrad Gessner, Gabriel Naudé, John Dury, and Gottfried Leibniz. The four librarians responsible for establishing the Bibliotheca Universalis are important figures in librarianship. Gabriel Naudé published Avis pour dresser une bibliothèque, the first printed monograph on librarianship. In this monograph, Naudé advocated collecting all kinds of books, old and new, of famous, more obscure, and heretical authors. He also contributed to the idea of organization and administration of libraries which led to the development of library collections. It was also in part thanks to Naudé that some libraries began to lend books outside of the precincts of the library. John Dury is considered to be the first English library theorist. He wrote two letters to Samuel Hartlib concerning the duties of a professional librarian, which were published in 1650 as "The Reformed Librarie-Keeper". He held that librarians should not only care for the books, but should also be well educated and accomplished to raise the standards of librarianship. Furthermore, he advocated that librarians deserve a living wage in order to use their energy to perform their duties to the fullest extent. Gottfried Leibniz upheld that the librarian was the most important factor in the aid of learning. He is credited as including science texts in addition to conventional literature within library collections. Another key figure of this time was Sir Thomas Bodley, who gave up his career as a diplomat and established Oxford's Bodleian library. He is credited as creating the first functional library of modern times. Subsequent librarians following Bodley were called Protobibliothecarius Bodleianus, Bodley's Librarian. They would earn £40 a year. The ideas formed with these librarians continued to develop into the 17th century. With the approach of Bibliotheca Universalis, libraries changed; the content of libraries became less selective, to include literature of entertainment as well as academic value. At this time, libraries also became fully open to the public, with access no longer restricted to a small circle of readers. In 18th-century France, two librarians, Hubert-Pascal Ameilhon and Joseph Van Praet, selected and identified over 300,000 books and manuscripts