While Biblical texts were the most common subject for medieval manuscripts, complete Bibles were prohibitively expensive to produce because of the sheer size of the text.
Nonetheless, some of the highest-ranking members of the European aristocracy like King Louis the Saint or Duke Borso d’Este commissioned magnificent manuscripts of the Bible, especially during the High- and Late-Middle Ages. These manuscripts are characterized by their impressive size and by the richness of their adornment because they were usually intended to be display pieces.
Unlike most medieval manuscripts, illuminated Bibles were primarily image-based, so the miniatures and other décor were usually added first and the text was inserted later. As a result, illuminated Bibles feature some of the most accomplished miniature painting to survive to today.
The invention of the printing press paired with the proliferation of vernacular Bibles provided a wealth of Bibles and became a catalyst for the Reformation as a result because increased literacy allowed more people to meditate on and question the teachings of the Catholic Church.