books and authorities

Are there any special rules concerning a book that's an authority on a subject?

Salvete Sodales!

The 4th ed. rules for authorities have been removed completely. But in many cases there are stats for the authorities in various themes. As long as Abilities are concerned they are considered as Summae with a pretty high level but low quality (in the extreme case of the bible as authority for christian theology this meant level 10, quality 3). There are also deliberations on the maximum level of books about Arts (I think in conveants).

Alexios ex Miscellanea

Fourth edition assumed that authorities were infallible and contained everything that could ever be said on the topic - you just had to look hard enough.

This is no longer true in 5th edition (with the Bible as a notable exception)- they are the books that laid the framework for a given topic, with other books building on it. They are not infinite sources of knowledge.

Gifted as Bonisagus might have been, his book on Magic Theory couldn't have too high a level: the theory had just been invented, and even in the 13th century it is still considered as flawed. The MT authority probably only described in broad strokes how Hermetic Magic works.

To me, authorities are generally widely-available low-level Summae, or even Tractati on which many commentaries have been written. Authors have a significant incentive to write such commentaries: it increases the quality of their book without significantly shrinking the target audience: what self-respecting magus would admit not having read Bonisagus's seminal text?

The term "authority" is used in 5th ed regarding core reference material for Academic Abilities, but there it merely means the author of the basics, the (indisputable?) foundation of the study, and only in terms of Academic Abilities (see p. 63, under Academic Abilities, P2). There are no special rules for them beyond what is said there, tho' as mentioned above, they do exist, and some suggestions made as to the Level/Quality.

(Actually, the Bible is the perfect example of what is NOT an Authority, in that previous use of the word. If Theology (Christianity) is "the study of God and his work in the world" (p 67), how can a perfect knowledge of the Bible teach one anything of the Saints, or of heresies? Of who the current Pope is, or what the latest papal bull was? Of the Nicene Creed and the various early Christian Councils, the Templars, the current status of Jerusalem, or current policies re Islam? Because the Abilities in AM5 are so grainy, each a broad umbrella for a wide variety of skill sets or knowledges (many constantly expanding and changing), no single author or book, or narrow set of such, can fill that bill.)