Can a spell detect the invisible?

Are there any ways in which a Hermetic spell might be able to detect things that are invisible, much like Second Sight allows someone to?

Although it in't really possible to detect species which have been destroyed, I'm thinking there may be indirect ways to achieve it.

As a first possibility, does The Discerning Eye allow one to see the invisible? The spell's description explains that it tell the caster whether an image has been altered by magic. Does that includes destroyed? The spell works though extromission, so it doesn't rely on the species that has been destroyed by the invisibility effect.

As a second possibility, InIm base 3 allows one to "Enhance one of your senses in one way". Could that enhancement be that you can percieve invisible things as if you had Second Sight?

As a third possibility, could an InVi spell detect the actual destruction of species as it occurs, much like it detect regio boundaries (which is Base 3)? This might not allow to see details beyond the ouline of the invisible thing, but would certainly reveal the presence of it.

(Note: Some or all of these may require penetration or a comparison between levels of the respective effects.)

My understanding is that, yes, Hermetic magic can detect the invisible. Discern Images of Truth and Falsehood is limited to analysing the species to see if they are real - therefore wouldn't detect an invisible character. However, the Discerning Eye spell instead analyses an object to see if the species are what the object or person would normally emit. Although the spell is explicit that it would detect invisible if it hits magic resistance and doesn't penetrate, my understanding is that a character which is invisible due to a spell has its image "altered" by magic (even if altered spontaneously makes us think of Muto, not Perdo), and that it is covered by an illusion - the spell is intended to detect what species something would naturally emit, therefore the distinction between the techniques shouldn't matter much here. The distinction here, is that while this will detect someone covered by an invisibility spell if powerful enough, it won't detect naturally invisible things the way second sight would - in this case there are no illusions to detect. However, other spells, such as Reveal the Lingering Spirit will help, just as I suspect you could detect an air elemental using InAu, for example, and you could detect Airy Spirits in other ways, like a Might detection spell. Actually, the Might detection spell is probably the most versatile invisible detecting spell there can be for naturally invisible beings.

Take a look at InIm in HoH:TL Guernicas section.

I did, which is why I quoted The Discerning Eye. :wink:

Still left me with questions, which is why I posted. The spell only mentions 'altered' images, which may or may not include destroyed ones (depending on the interpretation of altered). The bit about magic resistance only works if the invisible things has that. If it doesn't, there is no blank area, but does it reveal the invisible thing?

if it does, it might be worth clarifying the text. Because Discern theImages of Truth and Flasehood (ArM5 p.144) also uses the same word, yet it doesn't detect invisible things. Or does it? Is the difference between the two spells if that Discern the Images of Truth and Flasehood doesn't work if it doesn't penetrate, while The Discerning Eye does?

Eyes of the Bat will work if they’re solid.

In an old thread I did a pretty massive breakdown of Intellego sense spells and how they interact with MR. It boils down to 'sense' vs 'magic sense'. The first is just a spell that moves/manipulates your senses around while the second is a spell that creates a non-natural sense. The second is always affected by MR while the first often is not [once species leave the Parma, they have no MR]. The ability of 'sense' magic to often ignore MR does not exist for non-sense Intellego spells.

Possibility 1
TDE is a 'magic sense' that is not dependent on species from the target. It does not matter if the species from the target are altered or destroyed, it is the magical ones being projected by the caster that do the work. For an invisible target you would see both their original and invisible images, meaning just their original, if you penetrate. If you don't penetrate, then you will see a "dark spot" in the magical aspect of vision.

Possibility 2
Invisibility spells normally use the PeIm Base 4, which only destroys their Sight Species. InIm Base 3 "Enhance" to Sight would not help you since it works by manipulating species and there are none to manipulate. However any spell that can detect the other Species at a distance can overcome Invisibility (baring a higher PeIm Base). You could use InIm spells which use a sense at distance with a Range of Voice or Sight.

Touch is the one that normally make most sense for this type of spell. Hearing can be defeated by the target staying still and Smell will not always differentiate enough. While you run up against the targets Parma for Taste and Touch, Touch will give you a blank Magus shaped spot if it fails to penetrate while Taste might not be able to distinguish no taste from the taste of the air.

Possibility 3
InVi Base 3 "Detect regio" is not detecting species being destroyed and is worthless for detecting an invisible target. However any of the InVi Bases which detect active Magic would detect the invisibility spell if they penetrate MR (and the invisibility is high enough Magnitude for the Base used). Spells that detect Vis could also indicate something is off if the target is carrying any, though it would have to penetrate MR. Spells that detect the Gift would also work if they penetrate MR.

Not just Eyes of the Bat but most Intellego Form Target: Sense spells that do not depend on the Species of the invisible thing could work. As above, some would have to penetrate Parma and some would not so choosing ones that do not is best. You also want to choose ones that give you the finest grained sense.

EotB does not have to penetrate Parma and is a very fine grained sense. Even in Sagas where Parma could effect it, all that would happen is that you detect a Magus shaped blank spot rather than a Magus.

Sight of the Molting Magus (the spell right above The Discerning Eye) would have to penetrate to make the target glow, but any leavings from the target are outside of their Parma and so readily apparent to the caster. How useful it would be on failed penetration depends on how much activity has happened in the area recently since the spell gives an estimate time of separation.

I'm of the opposite view point. Imaginem can only affect "generators".
A magus generates imago that overwrite the image behind. If you PeIm, nothing will overwrite and the image behind passes through freely.

With that approach, you must use a different sense to detect the thing.


I agree. Perdo is all about destruction. The image is destroyed. There's nothing to see.

If a SG hates invisibility, one suggest the species needs to exist for a small amount of time. The justification being one cannot destroy something which doesn't exist. Then a sufficiently strong enough spell can spot the species before it is destroyed.
I personally think species destroyed, the end, is better, but RPGs and Ars are all about what the person who's running the game wants.

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Yes, there is nothing to see, however my understanding of the spell is that it compares the images projected (in this case none) vs the images that should be projected by the target - which is why is it subject to spell resistance - the species sent by the eyes of the caster connect with things and analyze whether the species the target emits is right or illusory. The spell isn't analyzing incoming images (there would be none to analyze here to detect the invisibility) - it's analyzing whether things are projecting the right species. If it was merely analyzing the species to see if it has been changed, I'm not sure why spell resistance is discussed at all. It would be a bit of an odd spell that detects invisibility when it fails to penetrate Parma Magica but fails to detect invisibility when it succeeds in penetrating it. So it's irrelevant here, I think, whether the species are destroyed because at the end of the day what is projected makes the analysis and the comparison.

Invisibilty spells alter the image of an invisible being, because they replace it with images around that being. They don't just cancel species emitted from an invisible being, which for HoH:S p.61 iconic species would just leave a lightless hole where the being was and thus make the spell useless.

With ArM5 p.144 Discern the Images of Truth and Falsehood a mage

can tell whether an image has been created or altered through a spell,

provided that the Illusion spell's level is equal to or less than the level -5 of DtIoTaF.

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Perdo means Perdo, not Muto. You aren't changing species but destroying them. And you can't detect altered species where there aren't any.

Also, when somebody uses a ReIm to move your image to a distance, in the original spot the real caster remains invisible, not a lightless hole.
In that case, any anti-illusion spell should detect that the image of the caster is being manipulated (without MR, since the species are outside the parma), but not the original place where it should be.

So, to me, to counter invisibility there are 4 options:

  1. A special "sense" to detect spells, so you can "see" where is the invisible thing.
  2. A magical "enhancement" to other senses to detect the invisible even without seeing it (being able to touch in distance, or a great smell sense or hearing should help to detect invisible things).
  3. A magical "enhancement" to be able to see and discern shadows more easily, since invisible beings still cast a shadow.
  4. A spell to destroy PeIm effects in area and good Pen :stuck_out_tongue_winking_eye:

The critical misunderstanding happening often is, that moving or destroying an image of a thing just involves affecting the species it emits. This is not the case.

Note that (HoH:S p.61)

Iconic species are carried in light

and Imaginem does not affect light: this is the domain of Ignem.

EDIT: See also here.

As Imaginem affects images, the resulting handling of species is sometimes tricky - and shadows are beyond its power.

Such an Invisibility spell is easy to invent but would fail its purpose: no need to publish it. Just destroying the species it emits leaves a featureless shadow standing around: anything but invisible. Destroying a visual image involves moving iconic species around the object made invisible.

Quite. So again ReIm - moving images - does not just move your iconic species away: it moves others in.

Also says that:

Species are particles that are continuously emitted from objects, and that, when they strike the sense organs of the body, evoke a response.

So, saying that you cannot destroy the species on the source using PeIm because they transmit through light, sounds like your interpretation.
Also, your interpretation means that all the invisibility effects should be Muto or Rego, yet they are Perdo.

I didn't even say that.
You can destroy iconic species emitted by an object. But you cannot destroy the shadow it casts. That shadow as such is then visible and featureless. This lack of features needs to be mitigated by moving iconic species from other sources onto the light there is around the object.

You could have written Invisibility that way. But once you stomach that you destroy an image with Perdo Imaginem (ArM5 p.146), not just iconic species, and for this need to move species from elsewhere, you can also design Invisiblity as written in ArM5.

Note, that the concept of species in Ars Magica was not published 2004 and could not be referenced in ArM5.

The concept of species is described in the core rule book for ArM5 on p79, in the Imaginem section.

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You are correct.

For the invisibility spells to work as written, it is the the new visual species generated by a wall, a person, whatever, which ocludes seeing behind the object, not the object itself.

Otherwise destroying the visual species of a person would result in a person shaped black hole, which would be useless. If species needed to be manipulated around the invisible person, there'd be a rego requisite, and there is not.



Let's look at an example: a grog in front of a red wall is turned invisible with VoI (ArM5 p.146).
That grog still casts a shadow and blocks light. Iconic species from the wall (HoH:S p.61) need light to be carried. There is hence no way to have light naturally pass through the grog to carry iconic species from the red wall behind to his front and turn him red. This still needs to be done by the VoI magic.

Just think of a chameleon turned red to hide before the red wall.

I'm confused by a lot of what has just been posted here. The guideline the invisibility spell uses doesn't say it destroys any species at all. It doesn't say anything about altering the image of the person. So I feel like a lot of these statements don't mesh with the guideline.

The guideline actually says it destroy's the thing's ability to affect sight (visual species). So the object can neither give off nor block visual species.

We also have to tread carefully with visual species and darkness, as we know in ArM5 that some people can see in total darkness. We don't know exactly what those people see, but they do see.


If there's a concept that wasn't decided in 2004 (and 2009), it would be that something stops the other optics species from going through the dagger. I haven't heard of such an effect on this forum until that one thread in 2020 or so.

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