Commentary on the Apocalypse (Commentaria In Apocalypsin) was originally an eighth century work by the Spanish monk and theologian Beatus of Liebana. Today, it refers to any of the extant manuscript copies of this work, especially any of the 26 illuminated copies that have survived. It is often referred to simply as the Beatus. The historical significance of the Commentary is made even more pronounced since it included a world map, which offers a rare insight into the geographical understanding of the post-Roman world. Well-known copies include the Morgan, the Saint-Sever, the Gerona, the Osma and the Madrid (Vitr 14-1) Beatus codices. Considered together, the Beatus codices are among the most important Spanish medieval manuscripts and have been the subject of extensive scholarly and antiquarian enquiry.