When a text is considered holy, it only makes sense to present it beautifully. An illuminated manuscript is a book or document where the written word is supplemented and often surrounded by elaborate borders, filials, arabesques, and tiny illustrations. Developed in the eastern roman empire between 400-600 CE, they exploded in popularity during the european middle ages, since creating illuminated testaments and prayer books was a popular pasttime for monastic communities with a lot of time on their hands. It’s worth noting that many historic Islamic manuscripts feature similar embellishment, but are typically referred to as painted, rather than illuminated.