A complete and detailed description of the Hebrew manuscript collection of the University of Leyden, primarily the collections of the distinguished Levin Warner, Dutch ambassador to the Ottoman Empire , and the preeminent Renaissance scholar, Joseph Scaliger, who took all knowledge as his province; both left their books in Eastern languages to Leyden. This collection is remarkable for its Karaite texts, which Warner particularly collected, but also contains translations of, and commentaries on, Arabic philosophy, the Hebrew scriptures, the Talmud, astronomical, calendrical, and medical texts, writings on other languages, and a treatise on gems, otherwise unknown.