Witold Kazimierz Czartoryski (1876-1911), son of Władysław Czartoryski and Marguerite Adélaïde Marie Bórbon-d’Orléans, was brought up among French and Polish elites, which explains his great passion for knowledge and his desire to explore the world in its cultural richness. During his short life, W.K. Czartoryski managed to collect over 25 000 books, stored in his little castle of Côte de Grâce in Honfleur, Normandy. This library was a truly universal, humanistic collection of exceptional intellectual value, concentrating on a wide range of topics. Its most important part concerned literature, religion and geography. The library also included a surprisingly rich collection of works on Masonry and nautical science. Most books were printed in French. Unlike other Polish libraries centered around the theme of emigration which were created in France, this one concentrated on the utility of the collection rather than on its Polish, patriotic nature. The paper presents the life of Witold Kazimierz Czartoryski and a description of the collection he had managed to create.