An astronomical book
The Leiden Aratea is an astronomical book in more than one sense of the word. It contains a work of astronomy written by Arateus of Soli, who lived in the third century BC. The images depict constellations: in some the stars can be clearly seen. The book is also astronomical for its sensational decoration scheme. It was made for Louis the Pious, likely at his court, in c. 840. The images, while medieval in origin, have a distinct classical feel to them. The red boxes around them, for example, are reminiscent of books from classical Antiquity, as are the style of the robes found on some pages. Carolingian rulers felt a special and close relationship with Antiquity and the classical echoes were included purposefully. Combined with the script used for the text pages (see the last image), which are copied in bold Rustic Capitals, it made a medieval object antiquated in a good way.
Pic: Leiden, University Library, MS VLQ 79 (c. 840).