Moving stuff by moving other stuff

In another thread the following issue came up.

Suppose I can push/pull/hold with Rego magic an object that's within the size limits of my magic (let's say a basic Individual, with no size modifiers); and suppose the object is solidly attached to another, larger object that would definitely be outside the size limits of my magic. Can I indirectly push/pull/hold the larger object by pulling/pushing/holding the smaller one?

For example, can I magically hold up a rope that fits easily within T:Ind, if a load that doesn't is hanging from it? Can I levitate the bottom of a large chest filled with gold coins, indirectly pushing up the whole chest, if the bottom would require no size adjustments but the chest as a whole certainly would (ok, I may need T:Part to target just the bottom, but that's a separate issue)? Can I hold a large horse in place by holding immobile its leather harness?

I'm particularly interested in:
a) canon references of what can and cannot be done in this sense (e.g. I vaguely recall some fyling castle from MoH where the only "flying" thing was a thin stone disc at its bottom).
b) problematic consequences of allowing or disallowing this "indirect action"
c) any elegant solution that "works", seems consistent with the RAW, and is easy to adjudicate.

Not sure about RAW with this, but I have seen rego animal used to kill knights. Simply stop the horse dead while they are at full charge.

Lifted from the originating thread.

Yes yes - gravity is a conservative force and all that.
But what's modern physics doing in Ars Magica all of a sudden?
The natural movement of cart et al are down.
To get them across, they must be held up.
Whether through a normal force or magic, it doesn't really change the mass, does it?

In this edition, yes. That's one of the many things I do not miss about the 4th edition, btw.

Could you point me to that spell please?

Ward the grog against stone. Base 5, +1 Touch, +1 Conc, +1 stone. Note that the ward is affected only by the size of the grog, not by that of the mountain (see the other ward examples, e.g. Aquam in the corebook).

But let's try to answer to the more general questions posed in the initial post in this thread!

Why not let the mountain shatter around him, entombing him in stone?

Sure, sort of.

Bad example, as you mention yourself.
In this case, +1 part or +1 size comes to the same.
If it is full of gold... not sure about that.

Would you let me levitate a tree (+3 sizes IIRC) by lifting only the core (+1 part)?

Immobile, no. Force it to stay in place until the harness tore, probably yeah.

Fairly vaguely :wink:
That one's in Legends of Hermes, chapter 6.
It has a +3 for size, and the wording "The spell causes the castle to fly at the running speed of a horse." LoH, p. 123

It kinda messes with the whole idea of sizes, sending us back to the 4th edition where a starting magus could make a flying castle easily enough.
Would need a friend to make it invisible/disguise it as a cloud though.

Generally I'd disallow effects that levitate something based on T: Part. That's certainly easy, and works.
Indeed, I thought I'd provided a solution back in [url]https://forum.atlas-games.com/t/catnip-garlic/129/1], stating that

My view of it would be that you are lifting/pushing/pulling part A of something, just like a strong person would.
How much weight of that material could your spell move?
You can push/pull object A and whatever it is attached to up to that wight - assuming the junction between A and the rest can withstand that force.

Therefore you can pull a heavy pack up a cliff by ReHe the rope, as long as the rope is strong enough and the pack isn't too heavy for the spell to move.

The unseen porter spell gave me this interpretation as it talks about a Str +5 person carrying something.

You can levitate a person by ReAn their leather armour but the armour may tear off causing them to fall.
You can raise a persons sword in the air, and if they have a firm grip they would rise with it.

Just imagine a strong invisible hand grabbing object A and lifting/pulling it.

All you need to work out with your SG is where the hands are grabbing. Is it on this side pushing, or on the opposite side pulling? Obviousy it is better to raise a heavy chest from the bottom by pushing up, but can you see the bottom to target it? If you raise the lid or sides they may break away.
Some things will need to be T:Ind instead of T:Part as you can't see the piece you need to move.

My trouble with what the OP proposes is that it uses the ReAn guideline: Manipulate an item made of rope. Manipulate to me has a very specific definition which is to handle or control in a specific (skilled) way. Certainly using a rope to tie up a wagon falls into this, but in my opinion it falls apart when you can expect to apply force to the end of the rope to pull whatever it is tied to along. At this stage the target changes to T:Part and the activity involved changes substantially.

IMO, the proper guideline for the pulling effect is the Base 3 Rego Terram Guideline exemplified in the spell The Unseen Porter. Please note this spell is really low level (10th) but it may have casting requisites. Such a low level, presuming it is known means that even with relatively low Art scores in ReTe it can be learned, and even when requisites do apply the spell will be successful for an unfatigued caster not in an adverse realm. Indeed, the guideline provides a suggested strength to gauge how much force can be applied.

Certainly The ReTe Base 3 (2) Control stone (dirt) in a slightly unnatural fashion mentioned above and the ReHe Base 3 guideline control an amount of wood, exemplified by Dance of the Staves, should be the threshold of determining whether or not one should be able to do something similar with a ReAn spell. At the very least a ReTe(He) or ReHe spell to move the wagon directly should be possible, and slightly easier than a ReAn spell to pull the rope along, because the ReAn spell to pull the rope has a higher difficulty due to the change in Target.

To me the important thing is whether or not I like the particular situation. If I smell abuse I'm disinclined to allow it.

E.g. A Rego Corpus specialist has made a ridicolously overpowered ReCo spell T: Ind so he can toss around a giant of he wants to. He also carries in his pack a severed human arm (enchanted with Charm Against Putrefication, we hope!). This is also covered by ReCo T: Ind.
And whatever he wants to move around, he simply ties this severed arm to - provided he has time to do so. So unless the block of stone weighs more than the Corpus T:Ind + several size modifiers he can do it.
IMHO that smell abusive (and perhaps also of rotting flesh...). It is beyond the whole idea to force such catch-all solutions to one Form. If you want to be specialized, expect to leave some of the other deeds to other magi.

However if a ReTe magus can float around a huge block of stone, I find it ok to have him sit himself on top along with - say a looted lab - since this mass is trivial compared to T:Ind stone +1 size, equalling 10 cubic paces which si some 25 ton.
Or if a magus with ReTe can levitate a wagon, I won't complain if the wagon is loaded with other things, but I dislike the idea that the horse comes along as well since it is connected by a harness.

I don't mind this, as long as the arm can support the weight it is carrying. e.g.
A disembodied hand carrying a basket of food? - fine by me.
A hand lifting a block of stone - won't the ropes cut into the hand and tear it apart?
Having a craftsman make a type of harness for the hand so it can carry weight - sure, but the arm will still be getting squashed by the weight.

I think it quite thematic that a corpus specialist would have body parts do various everyday tasks.

Ok, thanks a lot for the input. Let me see if I can summarize correctly the various positions.

Everyone agrees that if the small object is too flimsy, or too flimsily attached, something will break when you try to pull the large object along. No lifting a whole ship from a single nail in the hull, no pulling up a person by a single hair etc.

jonathan.link points out that his issue with the original post was that "manipulate an object made of animal materials" is not really "move it around" but more like tie a rope, turn a knob, or fold a blanket. That's a reasonable point, and I agree that one may want to require a level 3 Base for moving stuff around like in the case of Terram or Herbam (I'm not sure if he tries to argue that one should actually use ReTe(An) - if that's the case I disagree, and think that ReAn should be more than adequate to move an item made of animal products).

Everyone seems to agree that moving big stuff by moving smaller stuff attached to it should be possible, although a few people qualify it by stating something like "if the spell is strong enough". Well, that's exactly the point; is there a limit to the "strength" a spell can exert (except in specific cases -- damaging spells are an important class of examples) or is there only a limit to how large an item it can directly "grab"? I think that the example of wards shows that Hermetic magic in general is capable of applying an "infinite" amount of (resistive) force, so I guess ultimately there's no limit other than the sense of aesthetics and/or game balance of the troupe - the same limit that applies to every other effect "admissible according to the RAW".

I think there are actually several related but different types of Rego effects that move or hold objects. What's possible seems to vary a bit from one to another.

A by no means complete list.

General Telekinesis: Unseen Porter, Unseen Arm, Invisible Sling.
ReTe spells that can with Reqs target any inanimate object. Even something like say a rope made entirely out of plant material. These spells seem to be thematically limited to "applying the force" that a normal person can generate.

Form specific Telekinesis: The Flight Disk from Legends of Hermes, The Hermetic Engine from Trans Forming Mythic Europe.
ReFo Spells that move target's that are mostly of one form in way's unnatural to them. Often, like the above two examples, created to move objects not targeted by the spell along with them. The amount of force generated is way in excess of what a "human" can generate but usually has some finite limiter, Like what the target can naturally support and/or the upper speed it can move.

Domination: Wind at the Back, Strings of the Unwilling Marionett.
Forces a normally mobile target to move in a way it naturally can.

Animation: Walking Corpse, Lord of Trees
Allows a normally inanimate object to move like an animate object. The whole purpose is usually to then affect something not targeted by the spell.

Teleportation: Seven League Stride.
Instantly moves Target from one place to another without covering the intervening distance. Target can include carried objects with Req's.

Craft Magic: Err there's a bunch Nobles Parma.
Instantaneously rearranges objects into a state a normal craftsman can achieve. Guidelines keyed to a normal craftsman man hours. Not the forces applied.

Inhibit movement: Wards (And MR), Unyielding Earth, Flying Buttress, That Gyro Stabilized lance Spell from Soicitas.
Stops an object from moving. Often but not allways an all or nothing effect with no apparent upper limit of how much force it can oppose.

Enable movment: The Yielding Earth, and umm...I think their are more but can't really think of them.
Helps another force to move the spells Target more easily.

I'm not sure I'm saying that it should be the only way, as much as I'm saying that there is a generally low level spell that is well defined and limited and arguably spells that do something similar should conform to the limitations of the spell it is trying to imitate. Almost anyone can learn The Unseen Porter, only the poor magi who are Deficient with Rego or Terram are going to be in trouble with learning it. I think ReAn might be adequate, but see my comments below, too.

One of the things I like about The Unseen Porter is that it defines the strength that can be brought to bear on a problem like this. I have a desire to favor ReTe for telekinetic effects, because of this, and it makes sense that this spell is the general spell and utilizes casting requisites, which again is really easy (almost no real penalty) for such a low level spell, it can move pretty much anything. So, I would favor the application of The Unseen Porter here over other alternatives. Certainly I wouldn't allow a ReAn formulaic spell to be cast with casting requisites to affect any other forms like The Unseen Porter does. I'd probably also limit the strength to +4 for effects that aren't Terram based, but I don't have a rigorously reasoned explanation as to why...

The more I read the descriptions of Unseen Porter and Unseen Hand the more I think they are special cases and fundamentally different effects from other ReFo spells even other ReTe. Neither their benefits or limitation track with other Rego spells presented in RAW.

I don't disagree, these are legacy spells. Spells designed to move other objects, though are even less well defined, though.

Well the definitions are inconsistent. Some well described some glossed over. Many not relating much to each other.

There's the Flying Buttress Hermetic Projects 41-42. A free floating stone pillar probably around the size of a terram base individual for stone but able to support hundreds of times it's own weight without moving. Base 3 effect able to effect greater then it's own weight thanks to a +3 size modifier.

Then there is the Hermetic Generans Transforming Mythic Europe pg 125. Spining metel disk can be connected mechanically to Produce 1hp (equivalent of +5 Str apparently) for medieval mechanisms. Also a base 3 effect but if you want this one stronger you can increase the effect not the size. So a base 4 gives you 10hp, 5 gives 100, 6=1000hp.

The Flight Disk LoH pg 123. Stone Disk that fly's through the air at the speed of a running horse. Same level of effect and size modifier as the Flying Buttress. But this time the size is only because it's 300 paces wide. The fact that it can support a full Castle built on top is totally unacounted for in the numbers.

Huh? I'm referring to The Unseen Arm and Unseen Porter. I am not referring to spells in other books.

I take Hermetic Projects with something of a grain of salt, like Magi of Hermes. I haven't done a lot with Legends of Hermes.

No you where refering to

Well the OP asked for Cannon effects that move stuff by moving other stuff. Like it or not they are cannon. If you just want to discuss your own house rules you should say that.

There's canon and there's canon being correct and consistent with established rules and canon. There are canonical Creo spells in HP that are T:Structure, which aren't kosher. So, they may be canonical but they aren't always correct.

But thanks for telling me what I'm talking about.

Well, if it already has enough extra levels to support the weight (due to needing them to affect the disk) they don't need to be mentioned twice.

I think the HP spells have been errata'd. If you've found some that haven't been, send me an email.

Inconsistencies slip through, but I do try to errata them when they are pointed out.

David