As thou thyself seest, most students run hither and thither searching for books without being able to find them. . . . Look over thy Hebrew books every month, thy Arabic ones every two months, thy bound books every three months. Keep thy library in order, so that thou wilt not need to search for a book. Prepare a list of the books on each shelf, and place each book on its proper shelf. Take care also of the loose, separate leaves in thy books, because they contain exceedingly important things which I myself have collected and written down. Lose no writing and no letter which I leave thee. . . . Cover thy book-shelves with beautiful curtains, protect them from water from the roof, from mice, and from all harm, because they are thy best treasure. His fine linguistic sense and his conception of the art of translating are shown by his counsels on this subject.