A minor pet peeve of mine: Euclid's Elements (A&A p.136) should not be Quality 9 (8 in translations). It should be much, much higher, and has always been considered a gem by mathematicians throughout the ages.
The Elements, as the very title (Stoikheia=first principles, matter in its most basic form) suggests, is the quintessential primer, a very streamlined text meant as grounding for more advanced mathematics. It is evident by reading it that it was written by a mathematician who understood the advances of the previous two and a half centuries at a significantly higher level than that described in the Elements, and distilled what every student should see with clarity before embarking on more complex and less fundamental stuff (such as his own work on conics, or on hypotheses in theorem statements).
This is one case in which the ArM5 mechanics for summae really work: Euclid lowered the Level considerably to increase the Quality. If Euclid's tractatus on optica is Quality 9 (a lowish assessment, but still), and Euclid's Artes Liberales was 12 (i.e. no less than that Aristotle in Philosophiae), then the Elements should be a Summa Level 4 (as in A&A) but Quality 15 = 9 + (12/2-4)x3 in Greek.
Already covered in the insert on Gender Nonconforming. You can have a magus with a feral upbringing, but he doesn't have the Flaw Feral Upbringing. You could have a new apprentice with the Flaw, however.
That is a good point, and something of a fatal flaw for the spell. Well, at least for the description; I will errata that. The spell itself is still good.
ArM5 p 113 says that a base group contains mass equivalent to ten base Individuals, which would be about ten people.
OK. Most of the books are assigned values by people who haven't read them, so I will take revisions from people who apparently have. (My favourite was a book that was defined in an earlier edition as a summa on agriculture, level 6 or so. I actually read it later. It contains three sentences on agriculture — and they aren't that profound.)
Yes to the first and no to the second. ArM5 p.129 says
A base Individual for Corpus is an adult human being, up to Size +1.
Size +1 is roughly double the mass of Size 0, the size of a typical adult human. 10 x 2 x typical human = 20 x typical human. There are a bunch of other spells that affect 10 people, but they're just designed in a suboptimal way. This one actually says the limit is due to Group, and that limit is 20 typical people.
It could, right? The language isn't very specific. But if it only means up to and including Size 0, why write it that way?
Meanwhile, we have a strong suggestion from example spells in core that it can handle Size +1. Otherwise things like Preternatural Growth and Shrinking would nearly never work for growth.
Now, Animal is written more clearly, stating Size +1 or lower.
It would matter for Corpus spells if they need + 1 size or +2 size to affect someone with Giant Blood, for example. That's why it needs to be clarified.
Note that +1 magnitude adds +3 to admissible target size, so no matter whether a Corpus Individual is a body of size 0 or +1, adding one magnitude allows one to affect Giant-Blooded individuals.
Why would it not be consistent with Hermetic magic to take the two facts (i.e. a group contains mass equivalent to ten base individuals, and the base individual for Corpus is an adult human up to--and probably including--Size +1) and conclude that a Corpus spell with a target of Group would simply affect up to ten people, each of which can be up to Size +1?
EDIT: Never mind me. I'm wrong here. Thank you , ezzelino.
Because otherwise a spell to create or affect a large quantity of rather small animals/things (say, a swarm of flies, or a haystack) becomes very, very high level.
The only way "Group" Target would affect 20 individuals is if you consider Size +1 to be the standard size of a human. For a human to be Size +1, that requires taking a Virtue which makes them deviate from the standard Size 0.
Per p.113, "A base Group contains about as much mass as ten standard Individuals of the Form".
A ruling that Target: Individual is enough to affect humans of Size -1 through Size +1 (the range for small to large humans) does not change the standard mass of a human, ten of which is what is affected by Target: Group.
A Form's base Individual tells you the maximum size for Individual before needing extra magnitudes for size. For Corpus, this limit is Size +1, just as with Animal, and roughly the same as with several other Forms. Group can handle a maximum of 10x the maximum Individal can handle. Since Size +1 is roughly 2x the mass of a typical person and Group can handle 10x that, Group's limit is roughly 20x the mass of a typical person, divided up however fits the group.
The Mysteries p. 113
The text says that an initiate into Dream Magic may also have Magical Focus (Dream) or Potent Magic (Dreams), but doesn't indicate whether this is a Minor or Major Focus/Potent.
City & Guild, p. 89. The guideline for travel times with or against the river seem to be reversed. Traveling with the river: "Divide it [the distance*] by six for river travel with the current, or eight for travel against the current." This means it is longer to travel with the current than against it.
*Side note, this seems to be for time in days, but I don't think that's mentioned.
(Not sure if this is the sort of thing you're looking for, as I've not been closely following these topics.)