If it's arguable, it's not a fact.
It is a fact that it is arguable. It is also a fact that given the criteria of allowing those qualities to add to the quality of a tractus would result in the stated elevations in quality. It is also a fact that your snide commentary added nothing but hostility to the discussion.
That's true. I've always assumed that those guidelines was without resonant materials though since it would interfere with copying and i like to think of them more as a bonus rather than standard. Reading through the insert again it would seem i might have assumed wrong on that one.
Using resonant materials the amount of people who can crank out a Q10 tract should be well into the triple digits.
Sir, it is not a snide comment. It is a simple statement. I can make it clearer, if you'd like.
That is not a fact. It is your opinion that advanced craftsmen for bookmaking professions should be able to boost the effective level. It is an opinion unsupported by RAW, as the bonus for skilled professionals is simply listed at 1, and never increases anywhere. City and Guild discusses quality of items made, but it doesn't specifically address book quality, does it. Book Quality is Source Quality, and the workmanship of the professionals making the book does have an impact on the finished product, up to +3. Again, if it is arguable, it is not an fact. As I said elsewhere, skilled professionals could make the book last longer, but I really struggle with giving skilled professionals any more weight into the book creation process over and beyond the abilities of the magus himself.
A Com 0 magus without Good Teacher can write a Q3 Tractatus, with skilled professionals it's Q6, with resonant materials, it's Q8. The only way I would be comfortable with having skilled professionals add more than +1 each is if the magus spent time (meaning a season) with each one getting his perfect vision as to how the sections should be scribed, in relation to the illuminations and working carefully with the bookbinder.
It states that it adds the bonus to all uses of the crafted item. Studying is a use of the item. It is therefore implicitly included.
And a fact stated conditionally is still a fact. As I said it is a fact that it is arguable, it is a fact that if my reading is accepted it will add to the source quality. It is a fact that if I drop a ball on earth from a distance of 4.9meters it will hit the ground in one second. The fact that I do not have to drop the ball does not change that, the same way that there is an alternate understanding of the situation, namely that covenants trumps city and guild, does not change the factuality of the statement made given the conditions of that statement.
Then you have it settled, for you.
In my opinion this is an error, likely not caught in errata, and something I would HR against. The table would be free to overrule my veto, of course. Covenants, in my opinion sets the limit of skilled craftsmen at 1. I realize City and Guild came later, but why not discuss the outlier where a scribe has an ability score of 10, and what bonus he might contribute?
But humor me... What's the cost of getting workshops and craftsmen able to add +9 to the book quality?
It never says that essential traits do not add to totals. Anywhere. Essential traits are described in detail on page 54. It clearly states
New books frequently add new rules. Superior and Extraordinary items are not discussed up until city and guild. Of course it wasn't considered before. Covenants also does not discuss the outlier case of a baker with a skill of 10, and how she might contribute to aging rolls. Or how a smith with 15 skill would improve weapons and armor. It makes no more sense to exclude books than to exclude bread, or weapons from things that can benefit from extraordinary quality.
Profession: Scribe can only provide superior work. You could claim a +1 from that. Really, I think that the rules requiring all those fancy steps should be dropped. Profession Scribe is all you need to get the info down. Having Craft: Books, or Craft: Illumination should just be for the purposes of protecting the book from damage or making it pretty so it impresses guests/potential buyers. But if the binding and illumination does add to quality you would need two people at skill 12, and a team of helpers to get the requisite 24 workshop total.
Those kind of people aren't for sale normally. They get snatched up by any covenant who can find them.
No, it doesn't state that it doesn't add to totals, anywhere. You're right. It says it adds to roll and nothing else. I find the use of rolls there to be quite specific, since most things add to rolls and then you roll them to see the benefit. When something applies to a total, it is almost always explicitly stated, which it is not in this instance So, I lean towards this being explicit for things that are rolled. Writing quality isn't rolled.
Can you cite that quote, please?
I find it odd that a really well made book makes up for the knowledge contained within. You are basically saying that a Com 0 wizard with no other virtues with a score of 5 in an art could product a tractatus of at least 6 and up to quality 9( with resonance, if the scribe, binder and illuminator could each get a +2 from their workshops? The text itself is crap but you get all this bonus from the book?
Hit post too soon.
Well, since books of such high quality would be available, you've created a paradigm shift within the Order of high quality books being, relatively easily, produced. You've minimized the role (or roll!) of the magus to making books, and increased the importance of craftsman. That's not something that I'm really keen on doing.
As to the baker, that can either be part of the Healthy Feature boon, and just fleshed out and made real, or it could be in addition to the healthy feature. I'm not so concerned about magi and covenfolk living slightly longer as I am about Q17 books becoming common place with huge bonuses from craftsmen and Essential (Virtue) Writer +6.
So are you saying +9 bonuses are possible or not?
So? The point of those arguing for ubiquitous high quality works is that only good quality works are copied and distributed. Which is reasonable to a point, but it is only the highest quality works of those available that are copied and distributed.
Magi are exceptional only to the extent that they have The Gift. There is nothing in RAW to suggest that magi are different from the general population in any other way.
Also, as an aside, "attend[ing] college/university" is more a measure of wealth than exceptional ability, and academics are typically useless communicators.
So even using your numbers, if half of those magi have something better to do than write books for other magi, you are looking at about 25 writers. Which is about two good active writers per Tribunal. That doesn't seem like enough to swamp the Tribunal with exceptional quality books.
Also, another point entirely is that there are other reasons than quality to value specific books. A tractatus written by a Founder, for example, is likely to be highly valued regardless of its quality.
I have several editions of some professional books. Some are well illustrated and have nice graphs with clear texts. Some other versions do not. It is much easier to read the former and the text seems to be better and easier to understand.
Still, I would also limit the bonus to +1 as per Covenants and the like. For me the problem is with the assumption that the OoH hads extensive libraries, but that is me. The idea of the book trade equalling modern systems never settled well with me. or maybe it is that books should provide much lower XP levels to start with. But that is another discussion.
Xavi
Have you seen the title of this topic? I mean, it is about tractatus quality... If we're discussing possible ways to push Quality past 17, I can't see how ways to lower it are any less valid. 
I would substract the Magnitude of your Art from book quality. And get rid of Summae. The result is a much slower learning curve, I suppose, and a rise in the value of vis at higher levels.
Xavi
I've been playing around with this myself. I, like you, think Summae are the devil. As a matter of just shear comparison based on build points, they are ridiculously cheap. When a L15Q15 summa costs 30 bp and that's the same as 3 Tractatus of Q10, it makes the summa the better deal for anyone who has a score of 12 or less in an Art.
When you say magnitude, I'm presuming that magnitude =5 still, and so 0-4 is no reduction, 5-9 is -1, and so on?
A magus with an Art score of 30 would only get 4 xp from a Q10 tractatus, or 7 xp if they have book learner (you've just made book learner even more valuable)?
I'm not sure what's best for the game. Hunting down troves of tractatus is not less appealing then hunting down piles of raw vis. Perhaps more, as the former almost invariably involves interesting NPCs and is a short-term solution, whereas harvesting raw vis can be more of a "boar hunt" or be reduced to finding vis sources (which deprive you of further excuses to adventure, once the current stash of raw vis/tractatus is exhausted).
Perhaps adding a level onto a Tractatus to show the author's understanding. To me it is foolish for a Magus who has a 5 in an art being able to write something for someone with a 30 in the same art. If you limit the people reading to +-5 of the level then Tractatus become a bit tougher to use. Magi must seek out Tractatus by others are are close to their understanding.
That has a lot of extra bookkeeping.
Expounding upon that. Designing or finding tractatus in play necessitates setting the level of the tractatus, which was never an issue before, and not something I'm too keen to deal with. I'd rather, if limiting tractatus quality go with something along the lines of Xavi's idea and making it a function of the reader. Master of the Art with a score of 30, "bah, I wouldn't use this tractatus to wipe my ..."
He did cite it. Note the text you quoted. My bolds.
The indepth discussion of Essential Traits on RoP:M pg54 he cites actually doesn't mention a thing about rolls. The quick blurp about Essential Virtues you seam to be referencing on page 43 does use the term roll.
It's easy to understand how readers would pay more attention to the three paragraphs on pg 54 and not check pg 43. It's much shorter a and little hard to find particularly since you didn't directly quote it or cite it like Lamech did his reference.
Alse perhapes since Essential Traits can be acquired without the virtue you could surmise that Traits gained via the virtue are more limited.