Hannah Smithson and Giles Gasper were privileged to give a talk last week in Oxford at the Oxford Castle Key Learning Centre, as part of the Westgate Talks series. The excavations beneath the Westgate shopping centre have uncovered the original Franciscan house, Greyfrairs, established in 1224, and for whom Grosseteste was the first lector. It was a pleasure to meet Jane Baldwin, David Radford, who have organised the series, and Ben Ford the directing archaeologist for the dig. Some of the photographs of the artefacts Ben shared with us were stunning, a later13th/early 14th century stylus with sharpened nib, and some high quality book clasps. The excavations are extensive and have involved a wide range of activities for the public. It was great that the Ordered Universe could be involved, and we look forward to following the archaeological discoveries.
The talk, ‘Uncovering medieval science: An interdisciplinary exploration of the work of Robert Grosseteste’, moved through Grosseteste’s career and his connections with the Franciscans at Oxford and during his episcopal career at Lincoln. Running a diocese that, in the thirteenth century, ran from the Wash to the Thames, with 8 Archdeacons, 77 Rural Deans and about 2000 parishes, was challenging, especially for the energetic way in which Grosseteste wanted to go about pastoral care and visitation. The mendicant orders, the Dominicans and Franciscans, were a tremendous of support in this enterprise, notable for preaching and taking confession. The importance that the medieval Greyfriars in Oxford would continue to hold for the Grosseteste’s legacy was also stressed. It was to the friary that he bequeathed his library, and seemingly, his works, in finished and in note form. William of Alnwick in the early fourteenth century and Thomas Gascoigne in the middle years of the fifteenth, both attest to having seen and used Grosseteste’s notes in their Oxford setting.
The treatises on colour and the rainbow formed the basis for the rest of the discussion. The latter may well have been composed at the point at which Grosseteste was starting to lecture to the Franciscans. It is interesting to contemplate the scientific treatment of the rainbow, with Grosseteste’s depiction of the Virgin at the end of his allegorical poem, the Chateau d’amour, clad in a shimmering rainbow. The poem was most 
probably written for the community at Greyfriars. Hannah presented a new and refined version of the natural rainbow model which takes inspiration from Grosseteste’s theory of colour as he applies it in the specific context of the rainbow. Colour, he states, is light incorporated in a diaphanous medium: there are two bi-polar qualities of light: clara-obscura and multa-pauca; and one of the medium: purum-impurum. These he uses to explain the differences in colours within rainbows, between rainbows and in rainbows under different conditions of sunlight. The question session was engaging and informative from Grosseteste’s cosmology and legacy to natural science and human colour vision perception. It was wonderful to be talking so close to where he would have done, and to contribute to the wider communication of the importance of the excavations.