Whether it's thanks to the books, the sense of history, or the quiet environs, I've always found libraries one of the most comforting interior spaces I've ever inhabited. Give me any library, I'm not picky — it could be a university library, my neighborhood public library, or the library room at an older friend's grand home — I'm happy to just sit in a big, comfy chair among books.
To create your own timeless library look, start with the most important element — books! You may want to add some built-in shelves, or secure book shelves to the walls of the room. Add a worn, elegant Persian rug, some overstuffed library chairs, and a substantial, preferably antique table, and you're getting closer to realizing this look.
To see some other ideas I have for making this look your own,
A chandelier is always a nice touch, even if it's simply a candle chandelier, such as the one in the photo. Don't forget to add some foliage plants, whose oxygen production will help to stimulate your noggin. Potted palms or orchids are both solid choices. I also love the look of maps in libraries, whether they're in globe or flat form — it's a nice reference tool for any historical or geographical-based texts you may be reading. Throw in some beautiful paintings, and an eyecatching throw pillow or two, and you have the makings of a beautiful, comfortable, and timeless library.