Getting close to a source for f85r2

[Koen G]

Sears calls Tetradic diagrams a "versatile commodity" in this quote about an interesting diagram in You are not allowed to view links. Register or Login to view.:

The manuscript contains the works of Bede and Helperic as well as a poem on the Easter cycle written by Agius of Corvey in the year 863. A tetradic schema appears at the head of the poem, although unrelated to it in content. Remarkable for the wild, trumpeting figures of the four winds perched at its cardinal points, the rota is otherwise straightforward. The elements, seasons, and humors are inscribed with their qualities. The four ages of man—infantia, adolescentia, inventus, senectus—are written in roundels which, significantly, interlock with a central circle inscribed microcosmus. A tetradic diagram was a versatile commodity.