Editing Ars Magica (section)

===Realms of Power===
The overarching premise of the ''Ars Magica'' setting is that the "mundane" world of ordinary, physical existence is a place where four great supernatural forces have varying degrees of influence and presence.

;The [[Divinity|Divine]] realm: This is the supreme, holy force of [[Creation myth|Creation]] – [[God]] as represented by the scriptures of the [[Abrahamic religion]]s, and his agents in the world.  Divine influence diminishes anything not attuned to it (i.e. anything of a Faerie, Infernal or Magical nature) and is categorically opposed to all things Infernal.  One of the Order's struggles is in reconciling their avoidance of mundane politics with the inexorable spread of the Dominion (Divine influence permeating the land as more land is settled by Christian and Muslim nations and more centers of Divine worship are constructed).
;The [[Hell|Infernal]] realm: [[Satan]] and his demonic forces.  In the medieval context, this includes everything from Satan himself to illnesses and bad smells.  Demons are compelled to corrupt, destroy, and tempt all mortals to [[sin]]; while the Order of Hermes refuses to explicitly name the Infernal as their enemies (which it is assumed would draw too much attention and wrath to the Order), they have been forbidden from entering into agreements with Hell's minions ever since a corruption scandal nearly ruined House Tytalus in the 11th century.  As the evil/negative counterpart to the Divine, Infernal power also weakens the effects of any Realm not attuned to Hell or other forsaken spaces.  Infernally tainted forms of magic do exist, usually of great deceptive or destructive power, or acquired too easily for understanding, especially in order to tempt magi.  Anyone in the Order found guilty of [[diabolism]] is expelled and hunted down.
;The [[Faerie]] realm: Creatures of traditional [[fairy tales]].  These creatures are often capricious, sometimes malicious, but invariably addicted to (even dependent upon for their very existence) human attention, emotion and creative expression.  Despite such considerations, Study of the Faerie realm can be rewarding to some.  Magi are allowed to associate with the Fae (in fact, one House of the Order has become increasingly dominated by its members' pursuit of 'Faerie Magic') as long as they do not incur their wrath and thereby endanger their fellows.
;The realm of Magic: A mysterious arcane force, to which all magi (among other rare entities) are inherently attuned.  This is the power almost exclusively used to cast spells and enchant objects.  Magic and Faerie have some positive resonance with each other, reflected in either aura's benefit to the other realm's powers, and in that remote or lost pagan traditions can have connections with either (in some cases, Faerie entities seem to have 'replaced' Magical ones when the devotees of the latter either lost their way or became extinct).

Additionally, a "Realm of Reason" appeared in the Third Edition.  This was associated with skepticism and empirical observation, and its "rational aura" challenged most supernatural effects.  Many fans of the game consider this to be paradoxical and inconsistent, since applying reason and rationality to the world of '''Ars Magica''' should really lead to the conclusion that magic does exist and fairies are real, etc., and yet the "True Reason" promoted by this fifth realm posited the contrary, and thus resembled a delusional (yet effective) state of mind rather than a rational one.<ref name="reason2">[http://www.redcap.org/page/True_Reason#True_Reason_and_the_World_of_Darkness "True Reason"] {{Webarchive|url=https://web.archive.org/web/20140116150117/http://www.redcap.org/page/True_Reason#True_Reason_and_the_World_of_Darkness |date=2014-01-16 }} on Project Redcap</ref> The realm of Reason had additional counter-intuitive effects – for example, imposing penalties on wizard's magic use when in prominent mundane libraries, despite the predominant portrayal of Hermetic Magic as a scholarly pursuit.

Reason proved an unwelcome addition to the game; neither Fourth nor Fifth Edition have included this 'Realm', and all references to it have been stricken from the [[canon (fiction)|canonical]] setting.