Muto Magic, biological gender and essential nature ?

Hi all. First, let me apologize in advance for my english, it is not a native language.

I was wondering : can you change your biological gender in order to procreate with Muto Corpus magic ?
I know Muto magic cannot stay forever and thing tend to revert to their essential nature. But, during the time of the Muto effect, the essential nature is, in practice, changed and thing affected by the mutated effect dont revert to original (If you muto some ice in fire, thing incinerated dont come back when the fire became ice again).

Since I am not expert on sexual dymorphism in platonician/aristoteian paradigm, I was wondering if a fertile maga could turn herself into a man to impregnate a woman. A soon as the impregnation is made, the man can revert to woman, but the baby is "in progress".
(For inheritance question, my maga need a baby but cannot stand to lose time making it...all of this is SO mundane, you know ?).

I dont see why you could not, but gender identity seems quite fixed in some old paradigm, (changing gender at sunrise/sunset is a tainted virtue from RoP:I), even if other seems fine with it (faeries can make babies with anyone...Zeus was even fine turning into horse or rain to make babies :smiley: ).

Any thought ?

(PS : I know the issue can be quite sensitive in our days too, I dont want to start a political ruckus here, please stay on the "medieval paradigm" :wink: )

Well, faeries are weird, so I certainly wouldn't use Zeus as an example!
There are a few options based on your saga and opinions on paradigm. I would look at other muto examples, such as using Muto X (Animal) to turn something into a sheep, and then shearing its wool. Is the wool reverting back to hair (or leaves if you turned a shrubbery into a sheep) when the spell ends? If you MuCo(An) a person into a viper, does the poison they spit into a jar stay poison, or turn into saliva?

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and with a year duration you could get the maternal bonus if you develop fertility magic even though it is a male magus...

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Hmm interesting.

I suppose the answer would depend upon whether one considers the 'male' and 'female' qualities to include the capacity to procreate in the appropriate manner.

My own inclination is 'no' as some people are naturally infertile. If you want such a feat to be easy, I'd recommend making it a separate spell or maybe adding a magnitude or two. If you want it to be challenging, requiring a breakthrough of some kind might work.

As others have noted Faeries aren't bound by Essential Nature in exactly the same way that the Magic realm is...

First of all, thanks for all your answer. I'm glad this forum is very well alive even for any kind of questions.

If you are fertile, and fertility is gender-based (male-fertility, female-fertility), you can Muto your fertility to the appropriate gender, parralleling the "muto-gender" thing, no ? Maybe add one or two magnitude, for adding effect -or another spell, for that matter, it is the same principle-.
But Breakthrough imply that it is not in the hand of hermetic magic at the time (and my maga dont have the time to research that, even if fertility magic is huge fun and not so hard to integrate).

Even for infertility : It is said to be in the essential nature of human to be able to reproduce (AMp79) -or to no be able to, i guess-. If you are Essentialy Blind but you can see with a simple spell (at least during the spell is in effect), so I guess with a spell you can be made fertile (during the time of the spell).

On paper, it should work.
But I remember (poorly) my history course of Aristoteian view on the world, and that women are just a bowl were the male semen grow until it reaches maturity.
So my problem is this one :
Hermetic Magic follow platonician/aristoteian paradigm
AM world follow...well, it depends. Sometimes the AM world IS really the view of these philosophers on the world, sometimes, this paradigm is just the prism by which we interpret the world, but the world in itself is the world.

It is usually a very theoretical problem in play (except maybe for some weird Criamon or some roleplayed Disputatio), but in this case, the following problem arose :
If the world IS actually the platonician/aristoteian paradigm, the embryo is just sperm being cooked, not an actual "thing becoming", and, as such, is still "linked" to the father : if he became female again, the fecondation is canceled.
If the world is the real world, as soon as the fecondation is made, the father dont have aything to do with the growing of the embryo (and can become female again).

I must add that I just recall that "Hermetic magic cannot discern the mother from the child until the 3 week of pregnancy" (I dont remember where it is written). So, maybe a Muto spell in effect for more than 3 weeks could work despite the paradigm in action, because a human being is born after that time...

Anyway, I'm not sure Im clear here (my english is not Disputatio-level).

maybe depends on a finesse roll to get the plumbing hooked up right, so to speak?

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Look up AM (Ancient Magic) p.55 box Hermetic Magic and Mother and Child: "Hermetic Magic can target a baby in the second trimester, and onward until birth, as a Part of the mother, ... In addition, mainstream Hermetic magic cannot usually discriminate at all between mother and child in the first trimester. This is a flaw of Hermetic Theory, which is circumvented by the integration of fertility magic."

The Minor Hermetic Virtue Fertility Ritual Magic gives access to a new Target Unborn Child (AM p.55 box New Target: Unborn Child) from the moment of conception on.

There is HoH:S p.97 MuCo 5 (R: Per, D: Sun, T: Ind) The Succubus's Trick to change the caster's biological gender.
You can experiment in a saga, whether the semen thus generated can impregnate a woman, whether this requires a Mu(Cr)Co Ritual (as it may create a human being permanently), or whether this is beyond the limits of Hermetic magic (because it effectively may create a soul). Philosophical and theological discussions will certainly follow these experiments.

Ahh, thanks for the precise citation !
And that spell is nice. I used a level 15 MuCo before, but this one save level :smiley:

Well, It is not my purpose and my troupe isn't keen on philosophical and theological discussion : we play to have light fun, throwing fireball and animating thing to do our biddings.
Since I am the rule-lawyer my troupe turn to when a question arise, It my duty to post a question here to get a response or at least a feeling, which I will bring back to my troupe for our final decision (they mostly follow my advice), but in any case, we prefer to play Ars Magica and not discuss it theoretically ! (And for my part, outside Ars Magica, platonician/aristoteia paradigm bore me very much. Old and useless philosophy is waste of time -im more of an analytical enthusiast-).

If you don't wish philosophical discussions in your saga, you can just rule with the core book, conclude, that fertile human semen generated by Hermetic magic violates the Limit of the Soul, and be done. Yep, one can argue against it - but you will not.

And, I can either rule the contrary based on the corebook... I see nothing truly clear about answering my question in the corebook, hence the post.
I came here asking for input or thought to rule this point. I thank you for your answer, but "You and your troupe must think about it" is not really something I could use :slight_smile:
(If I didnt understand correctly your point, it may be because of my poor understanding of english subtilities, if so, my excuses)


The child fathered with the Hermetically generated semen must get an immortal soul, right? That immortal soul cannot have been created by Hermetic magic (ArM5 p.80). So where does it come from? (And no philosophy, please!)

In brief: your maga has opened a can of worms which AFAICS ArM5 has tried to keep shut. Resolving it in your saga opens that can: with consequences for stuff like the nature and composition of the human soul, how an immortal soul enters the body during or after conception, and whether a human really, really needs one.

Magi, as any fertile human, are able to produce immortal soul by reproducing. The question here is can Muto magic help a woman conceive with another woman (two fertile human able to produce immortal soul). So the answer is not as straightforward you want it to be (you are entitled to your opinion, and I thank you for sharing it anyway !).
The corebook says (in the Limit of Essential Nature) " All human beings are essentially human; mortal creatures with reason, senses, and the ability to move and reproduce. "

Plus, I must add that I didnt say "no philosophy", I said "no philosophy with my troupe at the table" (in response to your "do philosophy at your table to answer the question") : I specifically ask here for a view on platonician/aristoteain philosophy on the subject.

The limits of essential nature seem clear. Core rules page 79. " Any magic which violates a thing's essential nature must be maintained, and when power is no longer supplied the things returns to it's natural state. Thus, Muto magic always must be maintained"....."All human beings are essentially human.....and the ability to move and reproduce"..... "Men are essentially male, and women essentially female".

How I read this, is the magi mutates herself to a man, maintains the magic until the sex act is complete and job done. Well, fertilisation needs to happen. It may take multiple attempts, however, it should be possible.

There's been enough rape and pillage through Europe and the resultant children from said rape, that I can't see the medieval paradigm arguing the father needs to stick around until the child is born.

The magic is not creating the soul. A male and female are combining to create a soul. Something that is possible and not affected by hermetic limits.


I would argue the spell needs to last long enough for the seed to grow and be birthed and gain it’s soul, regardless of sex.

I would like to mention the magic isn’t creating a soul. It’s facilitating the growing of the vessel.

I forget the time it takes for a soul to finally inhabit the newborn. I’m rusty on my theology.

A troupe could easily rule that the process would create a false life, an empty shell without a soul.

Various ways to play it would be to have the child live the duration of the spell and that is all. Unless baptized... which could bring a soul or kill the false life.

Quite a few interesting interpretations and story ideas. Thanks!


The problem is that sex may be considered essential nature even if appearance has changed, and an essential male and female are needed for procreation. A modern biological view of gender, sex, and procreation are not necessarily applicable (phenotype, genotype, procreation as a copying process (which circumvents the temporary transformation issue ;)) -- unless you want to because it's more fun for you. I don't know how well known hermaphroditic reproduction was at the time. IIRC some animals can change sex (seahorses?).

By - very rough - Aristotelian philosophy the semen, not the womb, is the origin of the new human. That semen is in your case created by Hermetic magic, hence the prime reason for the immortal soul coming into existence is Hermetic, and we get a violation of The Limit of the Soul.

Here is the relevant quote from the Physica:

One way in which cause is spoken of is that out of which a thing comes to be and which persists, e.g. the bronze of the statue, the silver of the bowl, and the genera of which the bronze and the silver are species.

In another way cause is spoken of as the form or the pattern, i.e. what is mentioned in the account ( logos ) belonging to the essence and its genera, e.g. the cause of an octave is a ratio of 2:1, or number more generally, as well as the parts mentioned in the account ( logos ).

Further, the primary source of the change and rest is spoken of as a cause, e.g. the man who deliberated is a cause, the father is the cause of the child, and generally the maker is the cause of what is made and what brings about change is a cause of what is changed.

Further, the end ( telos ) is spoken of as a cause. This is that for the sake of which ( hou heneka ) a thing is done, e.g. health is the cause of walking about. ‘Why is he walking about?’ We say: ‘To be healthy’—and, having said that, we think we have indicated the cause.

( Phys . 194b23–35)

Making the Aristotelian take on conception unimportant in your saga is quite possible! But it goes against teachings relevant to 13th century - nearly all male - scholars, hence may cause in game discussions.

To some extend, you can also draw analogy from the spell creating food, without virtus, but a duration of Sun (for example): it can be eaten and the person will feel satiated. However, once the spell ends, she is very hungry - unfortunately, I cannot remember where I read that.
So you could argue that the pregnancy lasts until the Muto spell stops, which unmakes the pregnancy.
Does it mean that it would trigger the death of the baby assuming that the Muto spells lasted until after the birth ? That's a tricky one, and gruesome - you might want to check with your troupe according to their sensibility.
If you want to take the safe road, supported by the rules, Fertility magic integration is required. So either that's the path the mage wants to follow, or for the sake of expediency, she can find an ExMiscellanea who belongs the proper tradition (handwaving the integration) or possibly an edge wizard with the right virtues & skills to do it on her behalf. That would be my preferred option since it can lead to a lot of stories.

ArM p.77, Creo section, last paragraph.

But Creo doesn't work like Muto. If you create bread with Creo and some ritual (with vis) you can eat the bread and be nourished. Muto last only for a year max.

My take is : if you Muto something, the thing stay mutated only for the duration of the spell, but all the thing the mutated thing act on dont revert : if you muto a tree to move, when the spell end, the tree root were he was when the spell end, he doesn't teleport back to his original place. If the tree killed or destroyed something, this thing doesn't come back.
So, if you are Mutated into a men until the foetus became a distinct individual in hermetic theory (after 1st semester), the baby should normally continue his developpment alone in the womb.
The process of giving immortal soul is independant of the magic to some extend : the natural baby gets it when he is entitled to by the Divine, not by the maga.

(Of course you can add many stories on this, but that is not my point).

Despite the name, I dont see why fertility magic could be useful : we dont want to act on the child-to-come, just let him come naturally by acting magically on one of the parents. Fertility magic could be useful to, maybe, letting the baby be alone just after fecondation (negating the "one semester" limit of hermetic magic), but that's all.

It is, of course, my opinion for the time being (I had thought to digest thanks to you all)

Aristotolean Philosophy aside, I like the concept of a maga gender shifting in order to conceive a child she doesn’t have to carry herself.
It enables the concept of a Gifted Mercere forming an extensive family for a woman as well.

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