I have just published a new RPG work. Glosses and Commentaries is a short supplement for Ars Magica Definitive Edition, released under the Ars Magica Open License. It is available for purchase on DriveThruRPG and on Patreon.
In the medieval period, certain authors and texts were regarded as authorities on a particular subject (Aristotle, in particular). A lot of effort was devoted to glossing these texts, which meant adding information on the page to make the book easier to understand, and a lot of people wrote commentaries on them. This is not, however, something that the current Ars Magica rules really support — you might as well write a book as a completely original project.
This may reflect contemporary thinking about the importance of complete originality, or it may just be a matter of trying not to make the rules too complex. I know that I was thinking the latter, but I may have been influenced by the former. Covenants includes some brief rules for commentaries and glosses, but they do not really encourage their creation.
These rules do. The main tool they use for this is reducing the Source Quality of a book that is not a commentary, and has not been glossed. This makes the book worse as a source for study. The Source Quality of any book can be improved by glossing, up to the quality of a book under the standard rules, and a commentary can start with the same quality, if the author has access to at least six commentaries on the same work, as well as the work itself.
While these rules do not specify authorities, they naturally create them, and the supplement includes an example, Bonisagus’s original text on Magic Theory. Bonisagus was, in this example, a good teacher and writer (as he really needs to be, given his historical role), but later glossators have made even better versions of the text available. Similarly, people have written many commentaries on his text, and so if a maga wants to write a book about Magic Theory, it is probably best to write it as a commentary on Bonisagus’s work, because it is easiest to get access to other commentaries on that book. Thus, the glossed version of Bonisagus’s book is an excellent text on Magic Theory, and most of the other good texts available on the subject are commentaries on it. This makes Bonisagus an authority, without including rules for it.
It also makes it possible for a maga to turn her own work into an authority. Write a book, and then convince other magi to gloss it and write commentaries. Then have the glossed version and commentaries copied, and distribute them throughout the Order. It would be expensive, but it is another way for a maga to secure her legacy.
If you want to try this out in your own sagas, the supplement is available for purchase on DriveThruRPG and on Patreon.