The essay “On Libraries” (Latin: “De bibliothecis syntagma”) by the Flemish humanist Just Lipsia (1547–1606) laid the foundation for two humanities that finally took shape in the first half of the 20th century: library science and museology. The author traces the history of librarianship from the civilization of Ancient Egypt to the fall of the Roman Empire. The source of information for the most authoritative and famous philologist of his time were the works of ancient, Byzantine and medieval authors, whom he quotes abundantly, which makes the book a detailed anthology on the history of ancient libraries, as well as musae (museums) - ancient sanctuaries of the muses, distant prototypes of modern European museums. In addition, Lipsia's work is interesting as a kind of manifesto of European humanism, calling for a careful and thorough study of the cultural heritage of the past, and inviting the enlightened rulers of Europe, following ancient models, to revive and increase libraries, and the general public to learn from the experience of the ancients and strengthen their spirit with books.