Book Rules from A Family Affair
In the saga of A Family Affair, we're handling books differently than we did in the Saga of Stranggore.
Magi usually study from collections of books. Studying collections is exactly like studying from summae, on page 165 of ArM5.
You can improve a collection by adding additional texts. These can be ordinary texts or exceptional texts. If the Level of the text is higher than the Level of the collection, the Level of the whole collection improves by one point. If the Quality of the text is higher than the Quality of the collection, the Quality of the whole collection improves by one point. If both the Level and Quality of the text are higher than the corresponding scores of the collection, the collection improves by one point in both scores.
A single book can never improve the overall Level or Quality of the collection by more than one point.
Note that it's possible to add a single book to a collection and have the resulting collection be less effective for study than the single book was. For example, if the collection has Level 9 and Quality 10 and the covenant adds a text of Level 12, Quality 12, the whole collection would increase to L 10, Q 11, which is inferior to the scores of the new book. In this case, it's to the covenant's advantage to just use the single good book and ignore the collection. In effect, they are starting a new collection based on the new, superior book.
If you are tracking the individual books in a collection -- for example, if some of the books were written by player magi -- you can always have a character take a book out of the collection and study it as a summa, if that is to the character's advantage. If you are not tracking individual books, then just assume that there is no single book in the collection that is superior to the collection itself.
Ordinary texts use the rules for summae from ArM5, p. 165. You can study from an ordinary text as a stand-alone summa if you want to.
Ancient scrolls, rune stones, bottled dreams, enchanted texts whose pictures and diagrams change with the Zodiac, and other esoteric sources of learning are exceptions to the usual book rules. They can be studied like tractatus from the ArM5 rules; they have no maximum level.
An exceptional text may be studied exactly like a tractatus from ArM5, p. 165. It has a Quality score, which is generally on the high side (8-11). When adding an exceptional text to a collection, consider the exceptional text to have a Level equal to its Quality.
Only collections and exceptional texts may be studied. A collection works like a summa, and an exceptional
Book Rules from the Saga of Stranggore
In the Saga of Stranggore, there is no minimum score in Speak Language required to write a book.
We use an alternative formula for determining the Quality of a book:
Quality of Tractatus = Author's (Ability score or Art score/5) + Communication + (Speak Language score - 5)
and language specialties only apply to writing books if the character has specialized in using that language in reference to the specific Art or Ability that is the subject of the book.
All books in the Saga of Stranggore are tractatus. We don't use summae at all.
The main reason for this is playability. A tractatus is valuable to any magus, so it's always good to have in the library. Summae are of value only to relatively low-skilled magi. We don't want players to feel gyped because we spent covenant build points to buy a summa their characters can't use.
Also, we don't really agree with the model of learning presented by Ars Magica Fifth Edition. Having books that cover all relevant material up to a certain Art or Ability level arguably makes some sense for modern textbooks and the like. We feel that medieval books were few enough and short enough (remember, they were hand-written) that every scholar would potentially learn something from every book, even if he had already read similar books (for example, bestiaries). Therefore we think the rules for tractatus have more of the medieval feel we're looking for.