Permanent Size increases with Creo Corpus

I'd have to agree, at least for image sake. How that applies to Hermetic Arts though, not sure.

Even if that's the case I don't think the same applies to the feminine ideal.

Amazons?

Why not just enchant a MuCo into the familiar bond and be done with it? No warping from effects enchanted in the bond.

What if it's a nonGifted member of the Cult of Heroes being rewarded?

Interesting prospect. Ordinarily the closest thing to a permanent Muto effect comes from a magic device and would Warp you. But that, hmmm...possibilities.

Sure Wonder Woman might be my ideal woman. But I'm not sure that'd be the general consensus in 13th century Europe.

Note to self. Dig out Rival Magic and see if analogs to Shield Bracelets, Lariat of Truth, Boomerang Tiara and Invisible Jet can be made with Amazonian Magic.

Transforming Mythic Europe pg 58 mentions the potential to create stone with unnatural properties by adding a (Mu) Req to a CrTe ritual. It might be mentioned elsewhere but it's an option I hadn't considered in magic before. My interpretation is you are getting around the Limit of Essential nature by creating ex nilo. So it probably wouldn't be applicable in a buffing spell like here.

At the same time, CrMe and CrCo routinely get around the limit of essential nature for an existing being, to the same degree, by using ritual effects to raise characteristics. A permenant switch in gander, for example, is clearly a part of essential nature, but it is not clear that size is more essential than say intelligence.

The difference is that there isn't a platonic ideal of a "stupid human" that the person can be tied to.

There are however platonic ideals of "man" and "woman".

Hermetic magic can't switch you permanently from one platonic form to another (from man to woman, or from human to tree). But it can improve or damage your expression of that form (make you more intelligent(creo), or less(perdo), make you stronger(creo) or weaker(perdo))

Interestingly, there isn't a set of guidelines that subtracts points from characteristics...

exactly. Now, which side of the line does size lay on? Is being large a different platonic form? I would tend to think not, since despite having levels in AM, people range all over in sizes, so becoming permanently larger should be possible.

I'd think a mystery initiation would be more appropriate.

I would think that, if no other reason (and I've made my objections clear above), this should be weighed in terms of game balance. Opens the door to making every grog and battle-worthy character permanently Large, which is a 20% chance to not take a(n additional) wound level every time damage is received.

Same with any and all animals (altho' that may or may not fall under the same argument of falling within the "natural" range of sizes, depending).

Not that that's a game breaker, nor even unwelcome in some Sagas, but it's something additional for a SG/Troupe to consider before throwing the door wide open.

Well, you're looking at a 13th magnitude spell which is going to cost 13 pawns of vis, and entail a significant risk of botch. Even should a Mercurian learn the spell, it's going to cost 7 pawns of vis. Creo or Corpus vis, which is always in demand. So, it's not exactly an inexpensive proposition to make a large portion of the turb large. And that's discounting what it takes to learn the spell...

I'd allow someone to make a spell like that but if you extrapolate from the CrCo guidelines your talking a base effect at a minimum of PeCo 35. It's literally easier to just kill someone then to lower their attributes.

Well as I've said before in the real world Intelligence can be improved, as can strength stamina, or the ability to communicate. In fact pretty much all the base stats can fluctuate up or down naturally. Size on the other hand is pretty stable. (at least within the ranges represented by the statistic) Once somebody reaches adulthood there is no natural way they are going to grow by +1 size.

So based on that concept size is a bit more essential then Intelligence.

Or you could go the other way. The Creo guidelines exist so therefor the level of their base characteristics is not part of a human's essential nature. But altering size is a Muto guideline so size is part of an essential nature.

makes sense to me.

in the real world, yes. In Ars Magica, no.

Well I'll agree that there are no hard rules to model the sort of exercise that increases characteristics. So it fair to assume that those changes don't happen in the canonical setting. Drawing conclusions about cannon based on the presence or absence rules makes sense in many cases. Of course following the same logic leads to the second part of my post.

At any rate I do not like to assume that characteristics only increase through magic in the setting. If only because that means the only justification for high characteristics is inborn talent and magic. So in my own games exercise, hard work, and practice is as much a reason for a high Characteristic as fate and magic.