Inheritance, Attribution and the Later Degree Systems

The book presents the images as received material and attributes them to Pietro d'Abano, the Paduan physician and philosopher of the early fourteenth century. The attribution is the book's own claim rather than an independent record, and how much of the set is his, and where he had it from, has never been established.

Similar degree material appears in Arabic and earlier Greek sources in forms that are related but not identical, so the question is not whether the images have a prehistory but which one. That gap has consequences for how the later tradition is read. Sets of degree symbols produced in the nineteenth and twentieth centuries are often spoken of as though they were versions of one ancient system. They are better understood as separate creations that share a premise, namely that a single degree can carry meaning, and the atlas keeps them as distinct entries rather than folding them together. What can be said with confidence is that this book is the point at which the degree image became a printed, complete and portable set in Latin Europe. Whatever stood behind it, everything downstream in the Western literature runs through the version it fixed, which is why a fifteenth century handbook with obsolete tables is still worth a page.