Untitled by Leonardo da Vinci
Leonardo daVinci's notebook contains some of the most beautiful artwork I've ever seen. The notebook itself is also quite lovely. It is unbound, put together after his death from loose papers containing his work. Da Vinci was a lover of shapes and movements and often wrote in a style known as "mirror writing," which is a style of writing from left to right, usually needing a mirror to reveal the message.
The notebook of da Vinici is now in the Codex Arundel in London, England.