Jan Muszkowski payed a great attention to bibliophilia both through the social activities in the societies and associations, as well as a theoretical activity. As the secretary of the Polish Society of Bibliophiles, he wrote about the enemies and lover of book, and indicated the areas of discussion about the essence of bibliophilia. He noted that bibliophilia requires some special qualities of mind, character and temperament. In his theoretical considerations on the concept of bibliophilia, Muszkowski emphasized the aesthetic function of books presented by “the idea of a beautiful book”. The modern concept of book science, contained in Życie książki, presents the sociological perspective of bibliophilia. Defined by Muszkowski conception of bibliophilia and bibliophile seems to be still actual.