If apprentices are as close as most magi get to having children, then their apprentices may be the few people they should be making potions for, vs. the dedicated longevity expert.
The fact that people will trade when there is something to trade is part of the rich, if not always fascinating, detail of history.
Okay, both are fair points, and I'll accept that it might be plausible, though by no means standard, as the new edition suggests, for masters to make their apprentices' first longevity potions, but to me at least, the mechanics of the 'Hermetic economy' are crushingly uninteresting, and more importantly undramatic. There are just so many other possibilities for stories inherent in the Mythic Europe setting that offer so much more than all this scrabbling for ever-higher numbers on a character sheet.
LOL. Yes, I see that. It's funny because I'm a rules light player prone to focusing on story material. Yet I'm also a 'realist' if that's possible in this genre who's campaign is moved forward by reprocussions over new story idea. Because we have Magi moving towards their early senior years, the realist in me is very concerned with the reasonable number of longevity potion makers in the Order so I can fairly decided what sort of potions my players can by and what it will cost them. To much and my players revolt, to little and I have have five immortals in the game.
None of this relates to our on going stories, but in terms of keeping the friends happy and avoiding those conflicts we discussed in another thread, the discussion had had my focused attention.
I suppose the discussion is as relevant as you allow it to be. Perhaps that obvious statement applies to all gaming and gaming style. Hmmmmmm...
You are right, but equally ignoring part of the human side of the equation.
While many discussions might focus on 'the numbers' and 'mechanics' you also have to remember what the numbers and mechanics represent. Longevity potions represent extended lifespans. Extended lifespans represent greater power, avoidance of death/final twilight (attempts to counter or delay the unknown end), an improved chance to leave a 'legacy', more opportunity to pursue esoteric interests or research etc etc. The magi know how and what makes an effective LP, even if they may not use the same number-crunchng analysis the players use.
The same goes for stat increases. The magus I posted who actually has invented the high level CrMe increase stat spells is doing it purely because there is a recognisable difference in the quality of books written by those with higher Com. His motivation is building/writing/collecting a fabulous library and distributing it as much as possible. In this goal he sees a great service to his fellow magi, personal recognition and status, and the chance to leave a legacy. What more human and non-number-crunching sort of goals could you ask for? To get the best books into his library he must have something to offer. His own talents for writing are high (Com3 and good teacher) but he has heard of a way to improve them and is working on it so that he can write even better texts than his own current best. Then he will a) have part of the library he is working on anyway and b) something valuable to offer other great authors. He has gone so far as to spend seasons at Durenmar researching and talking to other visitors (and the head Librarian) and trying to find living authors of supreme skill and specialists in each art. He has then written to as many as he could find getting a great variety of answers.* There are a great many real story possibilities developing out of this quest of his - ones which would not have come about were he not to have worked on the stat increase rituals.
*The most interesting (not yet followed up) of which being some utter gobbledygook coming from an ancient magus who once wrote a Q15 tractatus (before Covenants and resonances etc)!
Corbon
I look on the discussion of the Hermetic Economy as setting up the framework upon which great stories can be told.
Players resonate with details. For example, I went and saw the props that they made for the Lord of the Rings movies ( I was lucky that they did a showing in Toronto for each of the movies ). It was absolutely fascinating the detail and time and energy they spent on trivial little items.
Many things that in the movie that could have been deleted and none would be the wiser had been worked out. They had several different languages and cultural touches so that the dwarven portion of Moria felt dwarfish and the orchish part felt orchish.
To be able to do that they had to think beyond the basic story so that they could then manufacture the items which they then used to translate the full scenes to the screen.
If you tell a story and say that a magus wants your help to discover a special mystery that the magus has heard might exist then the players are going to ask why does this magus need their help. A good storyteller has to be able to see what this magus is like and understand what are his capablilities and limits. How old is this magus going to be when the magus worries that longevity potions made by the greatest of magi have their limits.
It also helps to have worked out what is considered a legendary treasure to a magus. If the players are told the item is some special helm that allows the user to switch minds with another human and they then respond with a statement like why doesn't this magus make it himself because a magus of that age and ability should be able to make something like that in a season or two then you lose the story element from the beginning.
It also helps when your players come to you and say that while they may not be the master yet of a particular art but they would really like something ( be it book, potion, item, spell ) and have the means to bargin for such item, to be able to put a price on availabilty and cost.
All of these points can lead to better stories and a better saga as things will make sense to the players rather than having them ask questions like why a magi at age of 85 would be worried on the question of mortality when all of them have been able to have longevity rituals that are good to take them into their 2nd century.
A few things;
It has always been my experience that these sorts of things are taken care of away from the table in email (at least since the late 90's) and personal conversation between sessions.
I don't believe that there is a great deal emphasis on this than in previous editions. There are mentions of tit here and there throughout the published material because if you want the order to look anything like it did in previous editions the absence of such a trade is absolutely preposterous. The authors had a choice
rework the setting substantially
make the setting inexplicably inconsistant
tuck in a few hints regarding the tradeing of vis and longevity potions
They made the choice that made me, and I believe the lions share of the fan base, most happy.
Well, I whilst agree with some of these suggestions, and would concede that the 'Hermetic economy' creates story possibilities, I would maintain that there are more interesting things to tell stories about, and more interesting ways to tell them.
The quest for immortality, or at least great longevity, for instance, is a staple of 'magical' stories, but I can't help but feel that there are more interesting and personal ways to go about it than a character simply scrapeing the necessary vis together and buttering up a Creo Corpus specialist.
As I said earlier, this perception stems from my, and my friends', attitudes towards Ars Magica, and gaming in general. Most of us are historians, and none of us are committed Ars Magica grognards (to use a lovely old piece of terminology). Further, none of us are primarily fantasy gamers. For me at least, stories about love, betrayal, power and revenge; eternal, dramatic, human motivations, are always destined to be more interesting than ones about gathering vis and maximising lab totals.
I realise that I am creating a caricature here, but a good story should not depend for its interest upon the mcguffins of its setting, which is all that longevity potions, vis, and even Hermetic magic as a whole really are. I certainly prefer for the characters to have deeper and more complex motivations than merely living as long as possible and writing better books. As a player, I would feel cheated if those were the main foci of a saga. As a storyteller, I would feel that I wasn't doing enough to motivate and involve the players if those were their primary goals.
At the risk of sounding sarcastic, I could turn the Lord of the Rings example to suit my own point. The films certainly protrayed the details of a fantasy world beautifully, but I certainly wouldn't say that, with their lumpen adaptation of an already cumbersome plot, and two-dimentional characters spouting cliched dialogue, I found them even slightly involving. A story that was essentially a parable about futility of war and the nobility of human spirit became, for me, ten hours worth of CGI monsters and interminable slow-motion swordfights. That said, I'm sure everyone here has already argued the relative merits of the Lord of the Rings flms to death a thousand times, so I'll draw a line under that.
I'm not by any means trying to say that my choices about how Ars Magica should be played and run are better than anyone else's, much less telling anyone else how they should play the game. I'm certainly not trying to insult or annoy anyone. What I do wish to put across is that I believe these things can be pushed into the background, and that to do so is to the benefit of storytelling.
You surprise me.
As historians, you know that economics are at the base of any society, and that meaningful stories about human beings cannot just abstract from their economic background.
Are the the only stories involving economy which you can imagine stories of 'gathering vis and maximising lab totals', of bookkeeping and hoarding 
'Don Quixote', 'Notre Dame de Paris', 'Il Gattopardo', 'Abu Telfan' or 'Jude the Obscure' are of course not about quantitative economy - but what would be left of them if you took away the economic conditions of their heroes?
Now the economic background of medieval Europe is of course at your fingertips, so perhaps you can just wing it when telling stories of - say - suppressed Cisterciensian bearded brothers: why they choose their lot apparently of their own free will, and why there were still uprinsings of them every decade or so.
But history doesn't help you much to figure out the society of Hermetic magi, its power and reference structures. To tell meaningful stories about magi, you will want to know what for a magus constitutes a real sacrifice, an unforgiveable act, a serious debt. All this - as historians you know that - can only be determined within a social framework, which again you cannot really fathom without knowing its economic foundations.
So you should understand why it is of interest to look in the ArM5 rules for indications, how Hermetic economy (of time and vis) might work and evolve, and which structures and roles in Hermetic society it might lead to.
Kind regards,
Berengar
I think the quest for better medicine, and more money -- or more ability to get the things money can buy, cf. 'power' -- are also eternal human motivations.