My current Saga is rapidly approaching its first Tribunal (Hibernia 1221 FWIW, with Ballack presenting the Cathach and claiming Praesis for the English as the big thing happening). And once again, I'm expecting the PCs to bring books and Vis to the Tribunal to trade.
Last time I played a tribunal was early during the 5th Ed. run, with just a handful of books out. There was a bit on book trade in Covenants, but I didn't find that particularly helpful. Have there been hard & fast guidelines or rules on Vis trade / book trade or the Hermetic marketplace in general published in any of the books by now?
What vis is considered common, what rare, what would be standard conversion rates?
What's a good method to put a price on hermetic books? You can always swap at equal level, equal quality, but what if there's an imbalance? Is a book on hermetic art worth as much as a book on (hermetic) ability (e.g. Magic Theory?)
Thanks for any help, I'd be happy if I didn't have to make it all up myself... 8)
Well, Hibernia is supposed to be vis-rich, so probably all forms of vis are common. Faerie tainted vis is probably also pretty common. However, the Hibernians prefer to leave their vis at the sites until is needed, so the volumes of vis traded might actually be low (or arrangements are made at Tribunal, rather than physical trades, which are done later, possibly over several years).
HoH:True Lineages explains the Mercere vis exchange rates (basically, 1 Technique vis = 2 Form vis). This is probably a decent yardstick. Creo, Corpus and Vim vis will always be the most desirable vis (Healing, Longevity, Creation, Aegises and Invested Devices), but since magi can make it, Vim vis supply is higher than would otherwise be the case.
Books are a lot harder to judge. A Summae on an art is probably worth at least the amount of vis it would take to study from vis to reach that level (so a L15 summae is 120xp. If we (generously) assume studying vis yields 10xp on average, that's 12 seasons at (1,1,2,2,2,2,3,3,3,3,3,3,3) for 31 pawns of vis. That's not even accounting for the lack of risk involved reading a summae (vs vis study) or the fact that more than one magi can study a summae (as opposed to vis, where only one magi can study it). Your summae is worth less if the SQ is below 10, more if it's above (probably by 10% per point of SQ in either direction). You could argue that copies should be worth less, but copies reduce the value of the original as well.
Covenants pegs Tractatus at 2 pawns for a sound book (Q9-11?), 1p for less and maybe 3p for higher quality. I'd suggest that Covenants under-values Tractatus and a SQ10 one should be worth at least 3p, for the following reasons:
1.) You will probably study Summae until you are level 10 in an art (note a L10 summae using the above example is worth 10p), so studying from vis takes 3p at that point. Note that using the above rule of thumb, a L10 SQ10 summae (55xp) is valued at 10p, which is cheaper than 6 tractatus at Covenants rates (12p). It's just smart to study from summae and move on to tractatus later.
2.) You will probably trade away a Tractatus once everyone is done with it, getting some of your vis back. This depends a lot on the original circulation of the tractatus in question; if only one copy got made it will carry its value a long time, if many got made it will rapidly decline to 1p (or less) as everyone has a copy already - and wants to trade it away. This is a big reason for people to back the Cow and Calf ruling, as every copy debases the value of all existing copies.
Resonant materials changes the math a bit; a tractatus might be worth putting +1 SQ in it (unless it's a vain tractatus), but almost every summae is worth putting +2 SQ of resonance into it. On average, summae should have higher overall SQ than tractatus because of this; fewer copies mean the copies made will have more effort put into them.
covenants also places the value of a sound summae at the level in vis, so a level 15 summae is worth 15 vis.
The author is probably making 5-7p of vis per season of writing, which by most standards is pretty decent profit compared to vis extraction, especially if he can sell more than one copy (then it's 15-21p per season, a huge profit if he can sell 3 copies). It's very hard to find a sensible balance for this sort of thing.
For example, let's say a magus writes a L15 Q10 summae - pretty decent but not ground breaking. Most covenants in the trade-able region (let's assume the adjoining tribunals) probably already have a L8-13 summae at a minimum, so is it worth 15p for them to buy a copy? For the L8 owners, the answer is pretty much yes, unless the magi have surpassed that value already via other means. So even the lower end of the market is a 'maybe' on buying your book. Selling it for 15p seems about right in this case.
OTOH, if you can pen a L20 Q14 summae, even access to this tome is a marketable commodity (Durenmar and Triamore work in this fashion), let alone an actual physical copy. So the value of the books is very hard to measure, as it could be considered a vis source in its own right. Selling it for 20p is laughable, it's a wonder of the Order of Hermes worth at least a 100p (minimum).
On the other end of the scale, a L8 Q12 summae isn't hard to write (anyone with a 28 in an art and +0 Communication can write one, anyone with more positive Communication can write it at progressively lower levels) and took 2 seasons at most to write. 8p might seem over-priced for something that's essentially a vanity project.
The more I think on the matter, though, the more I dislike the idea of selling books for vis. This is the sort of thing Verditus magi do (to a lesser extent Mercere as well, but at least they are supporting the Redcaps), it smacks of dirty commerce (the Verditus, obviously, feel otherwise, but that's just them). Books would certainly be traded for other books, given as gifts or tokens of appreciation, and covenants or magi would approach renowned experts with requests that they put their knowledge to parchment and ink, a great honor, and the 'buyer' would show appreciation with appropriate 'gifts', but raw vis would just seem gauche (like giving him silver or cattle for his work). A magi who sells his authorship for mere vis might well lose reputation ("desperate"), treating his knowledge as 'mere' labor to be sold away. Things like crafted magic items, original spell texts or unique objects would be far more appropriate things to pay for your knowledge.
This would help explain why new (i.e. player, optimized) covenants often have decent summae on most of the arts. The surrounding magi, no matter how much they might dislike the idea of neighbors, will give them books just to show off how awesome/generous they are, simultaneously reminding the newcomer that that they can repay their generosity by not rocking the boat and causing too much trouble.
Nope!
As has been stated, Technique vis tends to be more precious then Form vis, because it's more versatile and in general harder to obtain (there are specialized Virtues that allow a magus to extract Form vis, but none that I'm aware of that do the same for Technique vis)...
... but that said, it's a very saga dependent thing. After all, you are the storyguide, so it's up to you to decide whether the local area (or the entirety of Mythic Europe) has a scarcity or abundance of, say, Intellego vis sources vs. Aquam vis sources, and Intellego vis consumers vs. Aquam vis consumers.
Ah ... again, highly saga dependent.
In general, you can't always swap at equal level, equal quality, because of scarcity issues. This is particularly true for high level summae. Maybe there are three different L16+, Q13+ Summae on Ignem floating around in a highly competitive market, but there was ever only one good magus specializing in Herbam with Good Teacher (or at least one whose work survived) - his work is L15, Q12, and the next best work is only L10, Q11.
But within one topic, there are solid reasons why the pricing in Covenants makes sense. Summarizing, you can't really trade poor tractatus, because there's no market for them, as good tractatus are rather cheap and wasting time on an inferior book would not be worth the meager savings even if that book were free; while an exceptional tractatus might trade for little more vis than a "good" tractatus (the lowest quality for which there's a market) to several times more vis depending on how many copies of it are in circulation. Basically, if you can write a tractatus better than, say all but a few dozen tractatus circulating on a given topic, then magi specializing on that topic - probably at least a hundred worldwide - will want to read a copy, and will easily pay a fraction of a pawn for the privilege (how this translates into a copy made for an entire covenant is a bit tricky, but a x2 to x 6 multiplier is probably fair considering that only a fraction of the magi will probably care about it). That's quite enough to make it worthwhile for you to write the book in the first place, considering that making copies of it is essentially free in a Hermetic economy; if you don't do it, or charge significantly more, there's probably someone who can write a tractatus at the same quality, or just a point lower, who'll do it. These are the "good" tractatus, probably around Q10-11. If there are already several dozen tractatus better than what you could write on a given topic ... forget it, nobody will want to waste the time reading your book, which is basically worthless and un-tradable and thus never enters wide circulation. So a few dozen authors in the history of the Order have probably written all of its tractatus in all the Arts and "mainstream" magic-related abilities (Penetration, Magic Theory, Concentration etc.); these are the highest Communication authors who were interested in the vis (yes, a few magi do not care about earning tons of vis). It's a little like, say, professional tennis players. There are a lot of people who would play tennis for a living, probably at least tens of thousands, but a few dozen make up for most of the tennis that gets watched on TV, simply because even the most avid watchers do not have the time to watch that many tennis matches, and if given the chance they'd rather watch the best players playing.
These pretty good books, we said, can be had rather on the cheap, because copies of existing books are virtually free to make, and if there were shortage on a particular topic there would be a strong incentive for the next best magus to enter the market and write a new tractatus at the same quality or just a single point worse. Now, there are a few books that are better. These command higher prices, but how much higher? Easy: either there's a monopoly or cartel for the book that keeps the price high, or there's competition. In the latter case, again the price is just as low as for the more common books because the cost to make a copy is virtually zero. In the former case, the cost depends on how much it's worth for the reading magus to read that copy over a cheaper, "baseline" sound book. How much are a few extra xp gained worth? It depends on vis scarcity in your saga and for a particular covenant, so prices are going to vary wildly, but they are unlikely to go beyond a full rook even for a largish covenant who acquires a copy under Cow and Calf, and they could be as little as 2 or 3 pawns.
This was about tractatus. Summae are a bit trickier. On the one hand, the author benefits from being not just a good communicator, but also a magus among the most experienced on the topic. This drives the author pool down significantly compared to tractatus (which even an apprentice can write). Also, high level summae require multiple seasons to write, and thus command proportionately larger prices to compensate the author. At the same time, a single high-level, high Communication author could provide all the summae needed on a given topic, whereas there's probably room for tractatus from at least a dozen authors on any given topic. Perhaps more importantly, there's a much larger market for summae, particularly for primers: almost every magus will eventually want to learn any given Art to level 5+ (or, say, Penetration to level 3+), whereas only specialists tend to study tractatus. All told, this suggests that Art primers of L5+,Q15+ (requiring an author capable of writing Q10 tractatus with a score of 20 in the relative Art) are even more available then tractatus of Q10+ (a L6, Q21 Summa, however, is significantly harder to write). Top Art Summae would, however, be significantly more expensive, not just because they require more time to be written, but perhaps more importantly because they require the time of old magi to be written, and this time can often really come at a premium. How much more ... is, again, saga dependent.
Covenants mentions that this isn't the case; Vim can be made without special effort, but it isn't particularly common in nature and so it allegedly balances out.
(Actually, I'd say it depends on whether the local Tribunal has a lot of apprentice sweatshops running or not. Just like any other kind of vis depends heavily on local distribution.)
There is a caveat for Low Quality Tractatus. Any tractatus that teaches the reader something new beyond simple XP is likely to be coveted out of proportion to its Quality. (until the goody it teaches becomes mainstream in the Order, anyways.).
One might be able to make it, but Vim is super useful, so the supply is invariably low. Vim can be used for longevity rituals, preparing items for enchantment, including improving one's talisman, and is often preferable over Rego for the Aegis of the Hearth. A 30th level Aegis eats up 6 pawns of vis. Reasonably, one can expect an average, non-specialized magus to distill 3 (extraction total of 21+) or 4 (extraction total of 31+) pawns of Vim in a season. That amounts to two magi-seasons of work to power the Aegis, which is a bit time intensive. I went with average, and not a specialist, because an environment where a covenant work is extracting vis, the specialist probably gets shafted a bit, unless he can keep a certain excess over what everyone else generates in a season. A 31 Creo Vim lab total isn't too hard to achieve, but 41 is much harder and gets into the realm of specialists or older magi...
If players are involved in creating the covenant and spending build points, I typically spend a portion on a vim vis source...
Umm...that has no bearing on my statement. Vim vis will still be more commonly available than 'natural' rates because magi can make it. I'd appreciate a direct quote (or page reference) on that. Pretty much every covenant needs a Vim (or Rego) vis source at a bare minimum or they're distilling Vim vis on a regular basis to fuel an Aegis, so it can't be that uncommon (and in general, hermetic life becomes very difficult if Vim vis is one of the rarer sources).
Probably 6-8p/year is the minimum I'd consider founding a covenant around. Most of that will still go to the Aegis, and the magi will squabble over the rest - still better than magi wasting their time extracting Vim vis.
Alternatively, a strong (6p) Rego source (to run the Aegis) and a small Vis source (2-3p) work very nicely together without providing the magi with tons of versatile Vim vis.
The thing is that there should always be a market for new, good quality Tractatus. Each mage can only write a number in a given art equal to the art/5, so usually this means 8 or fewer per magus, and each one adds to experience regardless of how much experience you already have. If I am at level 40 in an art then I have probably completed a summae at level 20 then read every tractatus I could find on the subject, and am studying from vis (which is expensive at 8 pawns for typically around 8xp) unless I can locate a new tractatus, so if a recap comes around offering a copy of a new tractatus in my chosen art for a pawn or 2 of vis, I would be all over that.
Hmm. I know I read it somewhere but apparently it isn't in Covenants or anywhere else in my collection. Mea culpa.
"Apprentice" is Hermetic Latin for "Personal Vis Source." 
Jokes aside, I imagine that distillation-related scutwork is indeed the kind of thing a peregrinator or other low-ranked magus does as his covenant service, as well as a favored use for apprentices. (Regardless of whether Vim is relatively common or not, the fact is that there's still never enough of it.)
A covenant operating under the Realms of Power:Magic aura weakening rules isn't going to let just anyone distill Vis.
The catch is ... how many tractatus can you possibly read over a lifetime? Let's take the rough (if somewhat lowish) estimate of ArM5 that magi Art scores top around 40 towards the end of their lives -- we could have higher numbers, but the order of magnitude of our result would stay the same. A score of 40 is 4041/2=820xp. Of these 2021/2+210 where probably provided by Summae up to level 20, leaving 610xp -- which can easily be covered by some three-score tractatus. Multiply by 15 Arts, and you get fewer than a thousand tractatus to cover virtually all the needs of the Order.
Now, how many can a magus who specializes as an author get to write in his career? Let's say (rather conservatively) that his Arts peak at something like 1 Art at 30, 2 at 20, 4 at 10 and the rest at 5. That's 30 Art tractatus per author, and 2-3 dozen authors can cover all the needs of the Order -- authors who need only spend one season every 2-3 years or so writing (including books on Finesse, Penetration etc.) to get both a fair vis revenue and fame. Double that to account for books lost over the centuries, an imbalance between Arts (so you make sure that Herbam and Aquam are covered too) etc. ... and compare these 60 authors to the several thousand that lived throughout the history of the Order to realize that the Order as a whole has enough tractatus written by its best 1-2% communicators to keep virtually every magus reading his whole life. This is Bonisagus' glorious vision come true!
How many you could read depends on a lot of variables, mostly economics. If you happen to be in a vis rich covenant which provides an allowance to its magi- in other words you don't have to spend a lot of seasons doing other things, you could in theory read 4 per year, if they are available and affordable, presumably from the point when you stop reading summae. Assuming this is roughly 100 years, that is 400 tractatus that one magus might want to read in a single art. Times 15 arts is a hypothetical max demand of 6000 tractatus. Of course that is assuming high quality tractatus, so there are probably fewer than 2 dozen authors of that quality in the order at a given time, and unless they are well organized the odds are that a number of tractatus may be less lost and more in a different corner of Europe than you are and nobody realizes you want a copy of this tractatus in part because you haven't heard about it where it sits in a library, while the new Tractatus is being actively marketed y redcaps looking to get their cut of the profits.
Right. But how many do magi read? Canonically, magi Art scores peak around 40. So that puts a limit on how many tractatus canonical magi end up reading in their lifetimes, and the limit turns out to be 60 good (Q10 or so) tractatus per Art. Note that the limit is not caused by scarcity of tractatus -- rather it's the other way around -- because if there were demand for Art scores up to, say, at least 50, the author pool could easily grow to accomodate that need. PCs are, of course, always the exception, but here we are discussing the setting.
This seems highly unrealistic, unless the magus in question has a Major Obsession 
Note that even with so-so tractatus (quality 8 ) this would lead to some 3200 xp from tractatus alone, which added to xp from summae would lead to a score in the 80s in the chosen Art. ArM5 clearly states that this is not what you find in the setting... or you would find L40 summae!
Economics is not the primary factor in how often you can read. If you're just playing a character to hit a high Art score, it's often easier to read and ignore everything else. The structure of the saga also has a vast impact on how much you can read. If your choice becomes one of adventure xp or seasonal xp, it becomes a bit harder to decide to read. Note, I'm speaking from RAW. I'm playing in two sagas, one house rules that you can use adventure XP and complete some lab work, and disallows other seasonal activities that generate XP. In the other saga, it's much the same, but we can also defer the XP until we are doing lab work. In both cases, because adventuring is a pretty active part of what the magi do, it's hard to focus on reading. You are also presuming that summae to L20 are readily available, and/or worthwhile to read. While you could, in theory, in the right environment have a character read for 4 seasons per year for many years, that is rather unrealistic. You'll never see a character who actually can do it (hooks, story flaws, personality flaws that trip into a story, or taking Master of None flaw, which would force one to read 4 different things in a year). In my personal playing experience, I can generally get two seasons to focus on advancing Arts in a year, on average. I had a few years with my character who took an apprentice early that he managed to get three seasons of Arts advancement. And as far his specialty, he's only been able to study his specialty of a grand total of 1 season out of the 52 we have advanced. Stuff always gets in the way.
Your theoretical model is only valid with the assumption of a magus not having story flaws, not having responsibilities to his covenant and a strong desire to only advance his Art score to the exclusion of everything else. Ignoring fortune and glory, a talisman, an apprentice, a longevity ritual (this is a pretty big one) and a familiar, let alone doing anything with high Art score like making items and inventing spells. As ezzelino points out, this is highly unrealistic, and I would even suggest that his point about Major Obsession wouldn't be enough to get you to 400 seasons of studying a single Art in a 100 year span. My personal opinion is that someone who had a Major Obsession with advancing his Art could probably get close to an average of 2 seasons per year studying his favored Art. I've seen characters do something close to that, but more often players aren't even that disciplined, and will end up spreading out their Arts, picking up utility spells, or spells in their second specialty before a heavy focus on a high Art score.
And to live to +100 you need a significant investment in CrCo. I think you're lucky if you can send 1 in 4 seasons on an art, and you almost certainly won't average more than 2 seasons a year working on arts in general.
The other seasons are eaten up creating spells, or magic items. Training a familiar or apprentice. Duties to your covenant. Going to Tribunals and Grand Tribunals. Dealing with both inter and intra Covenant politics. Collecting/Harvesting Vis. Dealing with the local nobles.
Not really. You can get to that age with a fairly modest CrCo total. And then there's the whole specialists angle and whether you think they'd be willing to sell longevity rituals in your version of the Order (canon suggests this is common), but then you have the issue of acquiring sufficient resources, and that takes time away from reading.
Well, even if someone is willing to create one for you. That person and you have to spend an entire season together in a lab.
So you need:
- someone with a CrCo total high enough to make a potion for you.
- That someone has to be willing to either A) travel to you and come into your sanctum (what) b) Have you travel to him, and you're willing to come into his sanctum.
- You need the Cr or Co vis. Everyone wants Cr or Co vis.. so it's in high demand.
- That person has to be willing to actually make it for you.
- He has to be within reasonable travel.
It could take over a /year/ of investment to get yourself a longevity ritual. So you're going to get the highest possible, because you want it to last as long as possible. But if you start taking it too soon, warp!
But lets assume you're a weather witch. You mostly focus on Creo, Rego, and Aurum. That's still 3 arts you want to raise fairly high. IN 100 years.. how high can you /realistically/ raise them?
Even if you manage to dedicate 1/2 your total seasons towards raising your arts. That's at beast 1500 exp to split between all your arts. And you probably had to pick up things other than cr/re/au.
But lets say 80% of your 1500 xp went to those 3. It's costs 465 to get a 30 in an art.
So you're at a 30 creo, 30 rego, 30 aurum. We'll give you an affinity to aurum, so you're at 37. And you have maybe 150 exp to spend on all your other arts.
Now, you get old.. and you decide to write your Opus on Aurum. First off, you can maybe write a L20 summae if you have affinity and puissant aurum.
So, maybe you write a L20, your SQ is bad. Magi comm tends to be low, but lets give you a +1 You can write 20/7 Summae(using core rules, or using covenant rules an using all the bonuses you can get your hands on.).
The chances that you have a +3 comm and good teacher are crazy low. But lets say in the rest of your years, having this plan all along, you went out of your way to have a Mentem master increase your comm, or you did it yourself. You also made a trade with some powerful spirit that could grant you Good Teacher virtue. (Cause you're wack. Even though clearly you don't care much about teaching.. since you spend 1/2 of your time studying arts).
So, maybe you can write a L20/SQ15 summae. in Aurum. But I would argue that the chances of that happening are super low. That happening for multiple arts? seems unlikely.