Since im bored and i want to see the world burn, i will answer to some of your other arguments
Yep, reading it, i'm with you. But that also means that if the source of the illusion its not a spell, it doesnt work That would mean that cannot discern powers or other unnatural sources...
Totally true, its an interesting road to follow I see that clearly invisibility could be an illusion (but only sometimes, remember that there are natural invisibilities too).
But for the sake of chaos , I will just add here that the description of Second Sight makes a clear distinction between mere concealing illusions and invisibility, like they are different things.
To me the difference can be relevant... taking the Second Sight description text, i could say that the PeIm effect is invisiblity while shrinking an image with MuIm (or moving it very far with ReIm) are concealing illusions.
We can also argue that MuCo to size -100 somebody its the best invisibility (and defensive) spell xD
From a logic perspective I cannot tell you that its not true But from the game perspective, when a single spell of not a very high magnitude can make obsolete illusions, invisibility and some virtues, all at the same time, it rubs me in the wrong way.
Specially when there are so many other ways to reach the same result... but at least those paths involves making different spells with more narrow purposes, instead of "One Spell to rule them all" ^^!
For your arguments, sure! But some people leaned on it to argument that you can detect invisibility from its species... when there aren't.
Also, this is ArM, we love to invest our time doing some medieval metaphysical exploration xD
Iconic species carried in light is ArM5 cosmology and explicit rules: see ArM5 p.79 and HoH:S p.61. No need to conclude it from the shadows cast by things made invisible.
This is not a consequence of iconic species being carried in light.
Illusions have no substance. But this does not mean that they can't block light.
Visual illusions might block some light - but as the iconic species created and/or controlled by magic do need light to carry them to those to be duped, such blocking is limited: no light => no iconic species => nobody seeing the illusion any more. Imaginem spells are also no replacement for PeIg spells causing darkness like ArM5 p. 142 Gloom of the Evening or Wizard's Eclipse.
Illusionary shadows are clearly possible. A good example is HoH:S p.68 False Window, which in a frame can create an entire landscape with changing light in it.
But illusions creating actual light require an Ignem requisite, like ArM5 p.144 Phantasmal Fire.
Illusions reacting to outside light might be tricky, if that light moves and requires adapting the shadows and highlights of the illusion's details. Brandishing a lantern close to an illusionary grog might reveal him as such, unless the mage controlling the illusion succeeds in a Finesse stress roll to control the shadows.
Deleting the shadows of an invisible grog requires an Ignem requisite of the spell and perhaps also some Finesse rolls, once lighting changes around him.
That is not needed. You just need to accept overlapping images - both real and illusory - covering each other. Optics - also medieval optics - explain this.
I think I have a concept that comes closer than any one Iād had in the past to fitting. Iām still not convinced there is any one theory that can really fit optics in ArM5, but I do strive to get close. First, the points I need to obey:
There is a difference between iconic opacity/transparency and luminous opacity/transparency. We see this with invisibility, where there can still be shadows. We also see it with things like visual illusions not casting shadows, which is essentially the same issue in the opposite ordering.
Perdo Imaginem should do what it says, stopping or at least reducing interaction with species rather than having it interact in different ways that both contradict the guideline and may enter into the domains of Creo or Rego. Itās also important to not simply divert iconic species around an invisible thing to avoid problems like an invisible section of a solid wall.
While HoH:S does not require light to transmit iconic species, just as it does not require air to transmit echoic species (HoH:S being consistent with Aristotle allowing water to transmit echoic species). The core book, however, is more restrictive, but also notably peculiar in its statement. Light is only needed for them to travel from an originating body, but that requirement is not made within an originating body.
Things like Second Sight allow seeing of invisible things and seeing through illusions.
Iconic species need to reach the eyes for someone to see, including an invisible someone. That would include, for example, a person with a translucent veil who becomes invisible along with their clothing; the iconic species need to get into the invisible region to reach the personās eyes.
So here is what I currently have, based on some suggestions by others above, trying to work within these 5 issues, and sometimes working with some more modern ideas that help create terminology.
If something is truly iconic-opaque, like a normal stone wall, iconic species donāt pass through it at all. Iconic species reaching at least somewhat iconic-transparent things pass through them as though originating from them (like Huygenās principle). Sometimes somewhat iconic-transparent things add new iconic species on top that overwhelm the other iconic species, such as when a theoretically opaque illusion is created. On the other end of the scale, āinvisibleā things are very close to completely iconic-transparent, so much so that the added iconic species are overwhelmed by the new iconic species.
Iconic opacity/transparency v. luminous opacity/transparency is preserved.
Perdo Imaginem is only reducing interaction with iconic species, having the thing become less iconic-opaque and produce fewer iconic species.
Iconic species are only transmitted through an originating object or via light. This does require accepting something like Huygenās principle that has not yet been discovered because Aristotle didnāt have magically invisible stuff to work with. Happily, this is an acceptance of something to fit the pattern rather than requiring anything to break the pattern.
Second Sight picks up on both the stronger iconic species and the overwhelmed iconic species. The more overwhelmed, the more difficult, as seen in the rules for Second Sight. This both allows Second Sight to see invisible things and to see through illusions. It also avoids having Second Sight interact with the thing, avoiding penetration.
Since the incoming iconic species pass through the invisible person, they still reach the eyes and an invisible person can still see.
However, this still does not answer the issue of being able to see in darkness, which shows up in multiple places. So it is still incomplete or incorrect; and thatās where Iām not convinced a single theory can actually work, though I remain hopeful. But at least for invisibility, illusions, and Second Sight it seems to fit well.
āDarknessā has been used synonymously with ācomplete darknessā in the books. Meanwhile they have used terms like ānear darknessā and similar for not complete darkness.
So more extromission? It could be. If it were just InIm, that would make a lot of sense. But it shows up in a whole bunch of other spots through Virtues. The whole extromission thing in that spell has been viewed questionably, and this would have it running rampant. Plus, youād have to start asking about detecting invisible things with MR and stuff like that. It could be, though.
Yes. I don't like the terminology - but I agree with the concept it tries to express.
With Aristotle, species are tied to substance and genus: they are philosophical concepts. Here is a 15 minutes lecture about them:
EDIT: If you'd rather have an academic text, read here. It might be faster.
Iconic species are roughly informations about a thing, that are perceived by vision and conveyed by light. They are not physical entities.
If objects block light, they also block the informations carried in that light. Making objects invisible with PeIm does not affect their property to block light.
But we need the information carried by the light they block (like the redness of the wall before which the invisible grog stands). That information needs to be passed, together with information about the light they were conveyed by. Only then can the species be passed along to the right light beam on the right side of the invisible objects.
In that sense, objects turned invisible by PeIm magic are also made transparent to iconic species by that magic. As even institutions can be required to be transparent, there is no problem with that word.
As that magic is Perdo, we are tempted to find a term of what the PeIm spell takes away from the objects to achieve this: saying that it takes away "opacity to iconic species" is really, really tempting. It sounds like even the operation of putting iconic species back onto light is just a result of removed opacity - though it isn't. We also need to use it even more figuratively than transparency above,
Thus I propose - after some consideration - to simply say:
PeIm magic turning objects invisible does not affect their blocking of light, but magically circumvents their resulting blocking of iconic species.
But in ArM5 we know for sure species are particles (physical entities), right? This is a place where ArM5 and Aristotle would seem to disagree and thus our examination of things would have to diverge at least somewhat from Aristotle's view. Why do we know they are physical entities in ArM5? While they may be weightless, mostly intangible and invisible, and limitless, we still know explicitly that
Species are particles (HoH:S p.61)
We also have spells like False Window (HoH:S p.68) which create magical species that can be blocked by MR. And there is Scattering like Light (HoH:S p.63) that turns something into iconic species that then later turn back into the material they were.
Does it? Last time I checked it could be read as if it's making clear that invisibility is a type of illusionary concealment.
It does make a clear distinction between naturally invisible things and things made invisible, however.
This is whole different discussion, about what the rules should be to provide the best gaming experience. This one is about what they, allow or imply as they currently are.
But I disagree with your statement in several degrees. The spells are not making Second Sight moot. Neither illusions in general, nor invisibility. They are not particularly low level either. To see through invisibility we are generally looking at a lvl 25+ spell, possibly more. And don't forget that both spells under discussion need to penetrate (one of them can tell you there is something invisible w/o penetrating, but sometimes that's not enough).
There are spells that make things obsolete. This is hardly one of them.
I accept it. I just don't try to come up with an unnecessary explanation for the underlying physics when it's not necessary. Magic does what magic does.
I also don't try to come up with an explanation on how a flame created with Ignem burns without a combustible material, for example.
And no, optics does not explain an image w/o substance (and therefore incapable of blocking light), while overlaping another, completely hiding it.
You are able to see through illusionary concealment and disguise, including invisibility, and can also see naturally invisible things such as spirits and the boundaries between regio levels.
As Lindberg puts it (DMP, Introduction), in this work, Bacon does not formally examine divine illumination of the intellect, universal hylomorphism, the plurality of forms (properly qualified), and the separability of soul. He restricts himself to presenting a full theory of the physics of light. Species is the first effect of any natural agent. As Lindberg puts it (DMP, Introduction), āThis is a complete physical and mathematical analysis of the radiation of force--and, thus, of natural causation.ā
The use of āspeciesā in this account is not that of Porphyryās logic or the perceptual notion of likeness. It isāthe force or power by which any object acts on its surroundings.ā It denotes āal-Kindiās universal force, radiating from everything in the world to produce effects.ā As Bacon himself notes, species [force, power] is the first effect of an agentā¦the agent sends forth a species into the matter of the recipient, so that, through the species first produced, it can bring forth out of the potentiality of matter [of the recipient] the complete effect that it intends ([DMS], 6ā7). This is a universal theory of natural causation as the background for his philosophy of vision and perception. Most importantly, species is a univocal product of the agent. The first immediate effect of any natural action is definite, specific, and uniform. This production is not the imparting or imposition of an external form. The effect of the species is to bring forth the form out of the active potency of the recipient matter. (DMS, 6ā7).
...
Recent scholarship on Baconās philosophy of nature, especially that of Yael Raizman-Kedar (Raizman-Kedar, 2009; Raizman-Kedar, dissertation, University of Haifa, 2009) places great emphasis on the importance of the concept of species for Baconās account of perception and mind. She is correct to note that Bacon places a kind of natural activity in the mind via species. This leads in her view to natural species having a direct role in intellectual activity as such. One could speak of the direct presence of material, corporeal species in the intellect itself (see section 5.2 above for Baconās complex discussion of the role of signs in animal and human knowing).
Of course, from there is still a long way to HoH:S p.61 species - but at least species as particles become likely. Perhaps the author, @Timothy_Ferguson , can enlighten us about it.
Anyway, once we have ArM5 species as particles moving in a medium like light, Imaginem magic can easier make them pass though invisible objects and enter light again once they are through.
There is also an ontological difference between virtus and species: virtus is a real being, and the capacity for the full realization of a potency; a species is its first effect, having a deficient being. Virtus exists absolutely in the medium; species exist there intentionally. Bacon had a unique understanding of the meaning of the āintentionalā existence of the species in medio. While among his contemporaries āintentionalā was considered equivalent to āspiritualā (though not necessarily āmentalā) and opposed to ānaturalā, Bacon thought of āintentionalā as having a weak and incomplete being.54 A species, Bacon wrote, in relation to a ārealā being is so deficient that it cannot be enumerated among the things of this world. It āis not called a thing, but more the similitude of thingsā.55
and
A species does not advance in the medium by locomotion; it regenerates itself in consecutive parts of the medium. The production of a species, Bacon explains, involves a true and natural transmutation of the substance of the patient, which is made by true generation (per veram generacionem). The patient in this case is any receiver of a species, be it the medium or the final recipient.64 A virtus, by contrast, passes through all sorts of mediums without affecting them; it affects only the substances predisposed to receive its influence.
Very much simplified: Bacon's 'species' are not things. But certain things have the 'virtus' to produce 'species' in a kind of Aristotelean "emanation", which pass through an adequate medium and affect a predisposed substance.
That works well to describe sensory species and was likely their inspiration. But also Bacon's species are not particles.
While a detailed discussion of what species were thought to be by ancient scholars may be interesting, I'm not sure that really helps us. In the real world, they were eventually proved to be incorrect regarding the senses. And in the universe of Ars Magica, where magi would be able to test these things, species may actually work a little differently.
All we really have, that we really rely on, are what the various rule books tell us about how the magic does:
The description of Second Sight tells us that invisibility can be either the result of "illusionary concealment" or "natural" (for spirits and regio boundaries). In both cases it can be seen by someone with Second Sight. (ArM5 p.67)
Intellego Imaginem has a general guideline to discern illusions. (ArM5 p.145)
To me, it seems that InIm can see through "illusionary concealment", no matter what the exact details of how it is achieved (PeIm destroying the species or a creature with the supernatural ability to become invisible). It probably cannot discern spirits (because they are naturally invisible). It cannot see regio boundaries -- that is covered by Vim.
I see... so basically, anything one does with Cr/Mu/Re/Pe Imaginem gets the light wrong. You create the illusion of a big castle? You still get blinded by the sun while resting in its shade. You make someone who's very fat look very thin? The shadow is still fat. You make someone's (heavy) clothes invisible? He won't look naked, he'll look ...matte black, like a ninja. Wizard Sidestep is almost useless in daylight against someone who know's what's going on.
Frankly, this is problematic. I don't think it's at all obvious to the average reader of the corebook.
And I've not even given significant thought to what happens with echoic or olfactive illusions.
It's really a bigger can of worms than Magic Resistance. I'm tempted to say that the easiest fix is that Imaginem works as Phantasmal Force in that other game, as illusions in most legends, so it gets the light right. Mechanically, it would just require Imaginem to be able to manipulate light "entangled" with species, to be able to remove an object's interaction with it, and to create an illusion of light which illuminates just as the real thing. Does not seem like a big deal, and way easier than the frustrating complicated thing this is devolving to.
Or just use Ignem requisites (and possibly a Technique) when you want something be an illusion and also have a shadow or similar?
It may be problematic, but light is clearly Ignem and species are clearly Imaginem. The notes about the invisibility spells help clarify that point if it's missed.
As far as illusions in general go, don't forget that glamours are essentially real illusions, and being real in that sense they will block light if the object they imitate would. So it's not like all illusions need to work this way. Just Hermetic ones when someone doesn't want to involve Ignem.
And to address the second question in your original post:
Not sure to what extent it was discussed in this thread, but as I understand this should rely on the standard mechanism of your senses. Ordinarily your vision depends on species, leaving invisible objects out of the scope of this guideline.
That would mean that cannot discern powers or other unnatural sources...
I see that clearly invisibility could be an illusion (but only sometimes, remember that there are natural invisibilities too).
, I will just add here that the description of Second Sight makes a clear distinction between mere concealing illusions and invisibility, like they are different things.