The 'Dragmaticon Philosophiae', was a reissuing of 

’s 'Philosophia mundi' (c. 1125), for which he is best known. The 'Dragmaticon Philosophiae' survives in eighty meticulously copied manuscript versions that were circulated over the next 400 years before the work was first printed in 1567 in Strasburg by Josiah Rihel.

Like typical T-O maps that illustrate the world as described by 

’s 'Etymologies', this map depicts the habitable world as a circle with east ('Oriens') at the top, west ('Occidens') at bottom, south ('Septentrio') to the left and north ('Auster') on the right. The cross section of the 'T' is rendered east to west. In the upper left quadrant, 'indicus mare', or the Indus River, is indicated very prominently. Also distinct is the lack of 'Europa' label that usually adorns T-O maps, here replaced with 'Hispania'. The fourth continent south of Africa suggests a possible cartographic lineage that traces back to by Spanish geographer, Beatus of Liébana (d. 798) who created 'quadripartite', or four-continent, maps based on Islamic sources. The quadpartite design could also come from a cosmological treatise of Jewish-Persian scholar Masha’Allah ibn Athari.

The diagram in the lower right corner of the bifolium illustrates the phases of the moon, which are the varying appearances of the moon as observed from Earth. The diagram follows the phases as described by Conches, including: the new moon, waxing crescent, first quarter, waxing gibbous, full moon, waning gibbous, last quarter, and waning crescent.

T-O world map (diameter fifty mm) and astronomical diagram of lunar phases (diameter fifty mm) on vellum, in red ink with yellow and green gouache; captions in brown ink; protogothic script written in two columns, on bifiolium recovered from binding.

This medieval world map and lunar chart, currently on a loose bifolium, was lost in obscurity before it was recovered from binding material from a later book. The map was originally painted in northern France in the late-twelfth or early-thirteenth century, and illustrated a manuscript containing a copy of 

’s 'Dragmaticon philosophiae' (c.1144–1148). 

In his writings, William of Conches discusses various aspects of the natural world, including the moon – its phases illustrated in a diagram in the lower right corner. His work was part of the broader medieval attempt to understand celestial phenomena in a way that integrated classical knowledge with contemporary medieval thought.

The map in the upper left of the bifolium shows us a rare type of medieval T-O map because the globe is divided into four continents instead of the traditional three, suggesting that the map maker may have been referring to the work of Beatus of Liébana (d. 798), whose maps were reproduced throughout the twelfth century, or perhaps from a cosmological treatise by the Jewish-Persian scholar, Masha’Allah ibn Athari (d. 815).

de Conches’s 'Philosophia mundi', was heavily influenced by neo-platonic ideas inspired by Plato's 'Timaeus' (written c.360 BCE). It ridiculed literal interpretations of the Biblical Book of Genesis, including the theory that Eve was made from Adam’s rib. In response to his work, Conches faced charges of heresy and was forced to revise and republish the 'Philosophia mundi' as the 'Dragmaticon philosophiae' between 1144 and 1148. Rendering the T-O sphere as a quadpartite globe could relate to a cosmological treatise of Jewish-Persian scholar Masha’Allah ibn Athari, who was also considered a heretic by Conches’ accusers.

A rare bifolium (two-page spread) from a late twelfth- or early thirteenth century manuscript copy of 

’s 'Dragmaticon philosophiae'. Includes a T-O world map and a celestial chart of lunar phases. The map, commonly known as a T-O map, illustrates an ancient doctrine of the earth split into the three continents of Asia, Africa, and Europe, bounded by waterways. 

An Early Thirteenth-Century T-O Map from William of Conches