This wonderful series of medieval cosmographic diagrams and schemas are sourced from a late 12th-century manuscript created in England. Coming to only nine folios, the manuscript is essentially a scientific textbook for monks, bringing together cosmographical knowledge from a range of early Christian writers such as Bede and Isodere, who themselves based their ideas on such classical sources as Pliny the Elder, though adapting them for their new Christian context. As for the intriguing diagrams themselves, The Walters Art Museum, which holds the manuscript and offers up excellent commentary on its contents, provides the following description:
The twenty complex diagrams that accompany the texts in this pamphlet help illustrate [the ideas], and include visualizations of the heavens and earth, seasons, winds, tides, and the zodiac, as well as demonstrations of how these things relate to man. Most of the diagrams are rotae, or wheel-shaped schemata, favored throughout the Middle Ages for the presentation of scientific and cosmological ideas because they organized complex information in a clear, orderly fashion, making this material easier to apprehend, learn, and remember. Moreover, the circle, considered the most perfect shape and a symbol of God, was seen as conveying the cyclical nature of time and the Creation as well as the logic, order, and harmony of the created universe.
The T, the Mediterranean Sea, separates Asia, Europe, and Africa, while the O is the surrounding ocean. Although the origins of the T-O map lie in the literature of classical antiquity, some of the earliest surviving pictorial examples occur in early medieval manuscripts of the works of Isidore of Seville.