OK, following the introduction of Accelerated Abilities, I'm a bit confused. The blurb says that arts are used in pairs while abilities are used individually... Fine, whatever.
But what of Goetia, which are supposed to be arts, yet are used on their own?
And what of Methods and powers, which are supernatural abilities but used in pairs?
I would rate them as accelerated abilities as well, and place the numbers of difficulty levels in par with those of hermetic arts.
Cheers,
Xavi
According to the terminology in Societates, Summoning, Ablating, Binding, and Commanding would be Accelerated Abilities. Similarly, Methods and Powers are something else, Arts that increase as Abilities ("Decelerated Arts"?). The rules didn't define Arts this way when we wrote Divine and Infernal, so it was easier then to just say that all of these things are Abilities, but note that some of them start at 0 and increase in the same way as Hermetic Arts.
Note that Goetic Arts aren't used completely individually - every use I'm aware of is paired with a Realm Lore.
So, it looks like we have several kinds of supernatural powers at this point, which I kind of like. It makes for a variety of types of magic, and each have their strong and weak points, though with Hermetic Magic mostly at the top, with a couple others, such as Hyperborean Magic, approaching it closely, and most only approaching the levels of spontaneous magic and in only a limited area of effects.
Ah, good point. Though Realm Lores are abilities, aren't they? 
Oh, don't take me wrong, I do like it too. I'm quite happy that the Hermetic magic doesn't exist in a vacuum anymore. I'm just a tad worried about rules consistency, that's all. I've banged on Forest Lore (Arcane) vs. Nature Lore (Supernatural) before, and I'll probably find other things to grumble about in the future. 
I just wanted to revive this in reference to an outlier from HoH:True Lineages.
The section on Fenicil's Rituals describes pre-Hermetic / quasi-Mercurian Rituals that are referenced once or twice in newer supplements (can't recall exactly which ones at the moment).
Each requires an Ability score but the text was written pre the concept of "Accelerated Abilities". Leaving them as standard abilities makes them an unsustainable XP sink IMO - would they work as Accelerated Abilities?
(I recall that David Chart wrote an HP article about the Founders which used Abilities for each Mercurian spell that were very similar in concept to Accelerated Abilities ie. 1 XP per pyramind point, not 5 XP per pyramid point to learn).
Thanks,
Jarkman