Intelligo Corpus spell: Range: Touch; Duration: Momentary; Target: Boundary, to detect if a specific person is within the boundary and where they are (note Boundary base size of 300 feet diameter). Similar to the Inexorable Search, but no Arcane Connection required - is it valid? Seems so to me. The limit to 300 feet diameter may make this more limited than Inexorable Search (depends on coverage of the map you use), but you could bump that with an extra mag or two for size. I found a discussion of this on StackExchange here but no clear outcome.
I detect someone using Intelligo (e.g., I find them using The Inexorable Search, or using the spell above, or I use Intelligo Corpus to detect there are 3 people in a room I touch), can I now target the person/people sensed, and if so, what range spell is required, considering I cannot see them?
(I hit against these questions while trying to see if I could recreate the magic mirror from Snow White - technically not possible with Hermetic magic as it needs the ritual target Boundary which items cannot have, but I ignored that just to see how it could work. I thought it would need a Target Boundary Intelligo Corpus to find the "fairest of them all"; then it seems to need to target that individual with Intelligo Mentem to read their mind and get their name; then finally it speaks the name (that last bit it is the easy part!))
I would say no. Your target is the person, not the boundary, and without an AC, you need to be able to sense your target.
Finding some person within the boundary should be possible, such as the fairest of them all. That may be what you want, but it is not similar to the Inexorable Search
Yes, you can. When you can sense them, you can affect them. However, you are still limited by the range, and Per/Touch/Eye/Sight all (virtually) imply sight. You are left with voice and AC. So maybe, there are a few cases where you can use voice on an unseen target based on magical perception, but most of the time you are still left with AC.
But how is finding the fairest of them all any different from finding the one with the large nose, small ears, brown hair, 6 foot 3 inches and 43 years old (i.e., the person matching the description of one who would be the target of an Inexorable Search)?
The target is the boundary, and the boundary contains corpus, and the magic is using Intelligo to determine information about that corpus within the target (boundary) - it doesn't seem to me like the target is the person at all. If it was, then it suggests the target of a spell to discover a property of a liquid is the property, not the liquid.
[Edit: perhaps there is something here about the physical characteristics being a property of the person, not the boundary? Perhaps the number of people in the boundary could be sensed (a property of the bounded area) but not characteristics of those people (a property of each person)...? If this is correct, I'm not sure where the line would be between boundary properties and individual properties though - could I sense all the children, or all the diseased people...?]
I'd disagree here - Intellego magic is less bound by the limit of Arcane Connections than other types of magic. Detecting whether there is a person behind a wall you can see is explicitly something it allows (pg 80, core book), which feels pretty similar to what Whitescar is trying to do here.
For casting spells on people later, you'd need to still be able to sense them. With a momentary duration you might be able to cast on them next round (depending on how generous the SG is feeling, and to what extent they're inclined to take a lead from the way Muto Vim spells work), but not any longer than that. As Loke says, though, you'd still need to meet the other requirements of the Range (and I wouldn't count "can see them in the mirror" for Sight).
I might be inclined to make the magic mirror a Magic Thing with the Divination Supernatural ability (pg 102, of Between Sand & Sea, and probably other places as well, although you want a non-Hermetic version rather than the Hermetic version in The Mysteries: Revised Edition) to get round the "boundary requires ritual" problem (or alternatively, a Faerie Charm which grants that ability to the user), although that runs into the new problems that Divination can't grant magical senses and only has a Momentary duration.
Gazing into reflective surfaces is an existing Divination method that gives +5 Clairvoyance (TM:RE pg 61).
Indeed. Though one thing that I don't think is clear from the core book is how much you can learn about those people - it refers to detecting if there are people behind a wall, but not whether you can detect what they look like, what they are carrying, etc. Perhaps this is possible but adds a magnitude... perhaps it is not possible at all...
EDIT: There is "sense a specific piece of information about a body" guideline, p.131, which is what I was using for the magic mirror's effect, but it isn't clear whether that applies to a target sensed at a distance. Or I guess, it's not clear what the limits on it are - as in, whether it can apply to everyone in a boundary. If we assume it can, it does seem like the original spell I suggested achieves Inexorable Search without arcane connection - although I have just realised, the base is 2 mags higher than "locate a person with an arcane connection", so when you add another 2 to 4 (or more) mags to cover a large boundary, you end up with a level 45+ spell, compared to the level 20 Inexorable Search.
if Intellego Corpus can detect whether or not there are bodies (the substance of corpus in truth) behind a wall then why shouldn't Intellego Imaginem be able to detect what species those bodies emit (i.e. what they look like)?
The InIm approach of course doesn't directly allow the magic to detect what the bodies look like, you still require a human observer to convert the detected species into knowledge about the appearance of the things that created the species. But that is a rather academic distinction that would not really matter to the case at hand.
Yes - but also, as I realised per my edit above, InCo at base 5 may be able to get information on whether they match a description. If that is valid, this could be a valid spell:
Mirror of the Jealous Queen
InCo 65 (Requisites: Cr, Im)
R: Touch D: Conc(Mom?) T: Boundary, Ritual
Cast this while looking into a mirror and saying "Mirror, mirror, on the wall, who is the fairest of them all?" The spell locates the fairest of them all (the person closest to a perfect example of a human) within the county boundary, then shows that person's image in the mirror. (Base 5, +1 Touch, +1 Conc (maybe not needed), +4 Boundary, +4 size, +1 Imaginem requisite & +1 Creo requisite to show image)
This spell does not seem to target the person, so it gets round that problem, but in that sense it also fails to replicate the magic mirror from Snow White exactly, because that one says the person's name, which would need a targeted InMe. And of course this is a spell, not an item, because of the ritual target, and a Hermetic breakthrough or non-Hermetic magic would be needed to instil it into a mirror. Perhaps the Wicked Queen just churned through huge amounts of vis and cast this every day...
Prying Eyes is Case 2, and works without AC, at touch range.
Note that Prying Eyes will not tell you whether John Doe is in the room. If you see him, you are certain. If you don't, he could still be hiding in the closet, or somewhere less obvious so that you do not think of looking.
The difference is in complexity. You have to add magnitudes for very detailed descriptions, which might still not be detailed enough to be unique. Except if you are searching for a specific target, which you then need an AC to, unless you already sense him and do not need the spell. That's how I read it, anyway.
I agree, however, that you can do what you suggest, analogously to smelling for silver or whatever; you search for a category rather than for an instance, so it is just a matter of magnitudes for complexity,.
A CrIm effect, copying the image of the person. Is that what you have in mind from MoH. It makes sense that you cannot cast magic through the image.
Non-sense Intellego magic, such as Prying Eyes (no reason why a boundary version can't be made). This allows you to actually sense what is out of sight. I think you can then cast spells at voice range, if they can hear through the wall. Clearly, you cannot use sight range, because the target is out of sight.
Magical sense spells (souch as eyes of the Eagle). This should be trivial. You do actually see. The target is within sight. In principke the target could be sensed without the spell, even though it could not be singled out.
You wish to affect something by using a description of it. Hermetic magic has no way to find or target "the biggest guy in the room", "the fairest maiden in the land", "the man closest to the wall" or such without an intelligent being processing information and making decisions.
Yes, ritual Intellego magic can tell you, whether there is silver within a T: Boundary, or whether there are women within. Hermetic magic can also affect the silver or the women within T: Boundary. But Hermetic magic appears to have no means to zoom in with a description of an individual, and to then localize it.
"Tell me where the Pope is right now!" doesn't work without an AC and quite some Penetration, just by having Hermetic magic sift through the Vatican.
Something coming pretty close is a T: Vision spell like ArM5 p.153 The Miner's Keen Eye with its "+1 see through intervening material": send your Vision through the walls of the Vatican, penetrate the Pope's magic resistance to see him, and hope that you then recognize him on sight.
Snow White being a literal faerie tale, I'd assume the magic mirror was just a faerie and it was messing with the queen's head. Though she did ask the wrong question - "the fairest" can be interpreted as the most beautiful or the literally palest (fair skinned), and she wasn't called Snow White for nothing.
If she had asked who the most desirable in the kingdom was, she might have gotten an answer more to her liking. Snow White had these tiny little eyes set six inches apart and all the curves of a hat rack.
Why don't you think InCo can tell you who the biggest guy in the room is using guideline 5: "sense a specific fact about a body"? I don't see how any intelligence is involved in this other than the magus' own - the magic is simply finding something matching the parameters it is given, as Intelligo always does.
Yes, but if it can do this, why can't it find and affect everyone over 6 feet high? Or everyone with black hair? Or 6 foot high people with large noses, black hair and 43-years of age? As Ioke pointed out above, this seems to be a matter of degree of detail you want to detect rather than any clear division between individual and group descriptions. If my descriptors happen to match one person only, there seems to be no reason why I can't detect them if I can detect anyone at all.
So we agree about (1) not working. (2) would violate the requirement for Hermetic targeting without AC, that you need to sense the target, not an Hermetically created image of it. If the magus of (3) uses Eyes of the Eagle only to identify the target of his next spell, and can single it out afterwards by normal sight, that spell would work.
Have a look at TMRE p.94f New Range Line: "The advantage of Line Range is that it extends as far as Sight but does not require that the magus can see the target. However, he must be able to sense it in some other fashion: Hermetic magic cannot in general affect an unsensed target. For instance, the magus may hear someone talking on the other side of the wall." So if the guy seen with Prying Eyes talks and can thus be heard, the Hermetic Geometer can affect him with a R: Line spell, after he made his computations right.
But the spell explicitly says you can see the target, and the Intelligo Imaginem guidelines say "use a sense at a distance," so you are sensing the target, unless they made a huge error in RAW and used the wrong terms.
The Line Range stuff is very interesting - hadn't come across that.
EDIT: In fact, according the Intelligo Imaginem guidelines, it seems that it is possible to see any point in a boundary, in the same way you can see into a room, and then target the person you see.
Yes, a caster can sense the size of all the men in the T: Boundary with a ritual and successful Penetration rolls. He can then also derive the biggest man of these. But he cannot target that man then just as "the biggest man". See the qoute of TMRE p.94f New Range: Lineabove.
Ah, so if I am reading you correctly a spell such as Mirror of the Jealous Queen that I posted above would work - in that it is identifying a person based on a feature, then showing an image of that person? Or perhaps you think the second part is not possible, but it seems to me that if you can sense the man, there seems no reason not to be able to also sense what he looks like, with appropriate magic.
You are not representing the guideline for InCo very well here. Because when you sense "the biggest man" you are not sensing just a single fact about one person.
Your spell kind of has 2 steps to it:
Step 1: You are asking the spell to figure out the size of all the men inside the boundary (I assume its a boundary spell) and
Step 2: tell you which one of the men is the biggest.
You could absolutely get a spell to determine the size of a man, even a man that you cannot see as long as you can target him in some other way, such as by a boundary target. and following that logic you also can determine the sizes of a group of men, such as all the men in a boundary.
Usually hermetic magic is pretty bad at figuring stuff out, such as "which one of the men is biggest". You could have the spell generate a list and then analyze the list yourself.
the guideline according to your citation is: "sense a specific fact about a body" and I trust your citation but i very much dont agree that sensing a specific fact about a body multiple times must allow the spell to compare the facts too.
But of course the magic mirror in your example seems to have a mind that would allow such analysis. But then again if the mirror has a mind, is a thing of magic, a faerie spirit or whatever else, then it does not have to conform to the guidelines for how hermetic magic works.
I suggest you check out this other thread about how Magic things can deviate from hermetic rules in interesting ways: thoughts on a "Magic Thing"