A tradition of natural science books continued in the middle ages from ancient Greek and Roman writings through the early middle ages, when writers such as Isidore of Seville (6th century) and Bede (early 8th century) write treatises on cosmology and calculation of time. Later expanded at Fleury and taken further still by Abbo of Fleury, who lived at Ramsey in the 10th century and was an important intellectual link to the continent, the tradition flourished in Britain's monasteries. To these natural science books belong a tradition of diagrams which incorporate Christian cosmological doctrine into classical theories on the structure of the heavens and earth, uniting geography, physics and computation of time to demonstrate the harmony of creation. Books such as this one (which is in two separate manuscript fragments in the British Library) would have been textbooks for training monks and churchmen. This book was made at Peterborough, as shown by the annals written on its first pages. This diagram is a perfect example of how this natural science tradition related biblical 'numbers' to those of the natural world to structure an image of cosmological harmony. In the centre of the diagram, the vesica-shaped figure stands for God / Christ enthroned in heaven. Christ is surrounded by the four evangelists, and on the outer border the apostles and Paul, whose names are written in circles, and names of Old Testament prophets, priests, and patriarchs between the circles. Around the outside of the diagram, notes of the hours of the day and night and the names of directions (in Old English) and winds place the celestial scheme within the structure of the world or creation. The inscriptions on the sides of the central rectangle concern the 'sprinkling' of time throughout and the single voice of the gospels.