This is a great model that has endless applicability. One can find isomorphisms and homomorphisms in lots of other good models of mind.
I’m going to use what I think are some Deida’s original teaching examples, which are maybe sexist but are intuitive and fast. Mistakes are mine.
So take a kid who has feelings, this little dude feels stuff, wants to feel, wants to express feelings. And take a girl who wants to feel beautiful and express beauty. These are two parallel examples.
The little dude then learns that to be a “real man” he has to hide his feelings if he has them and even better not feel anything at all. So he figures out how to do this, even if somewhere he has a sense that something is very wrong.
The girl learns that she can’t be seen as a slut or sexual at all, and she has to be grim and serious and professional to be taken seriously. So she hides her beauty and the expression of beauty, perhaps even from herself, even if somewhere she has a sense that something is very wrong.
So, later, the dude and the girl/woman, in their early or late twenties or even later, or actually even as early as their teens, are eventually like wtf. But, absent proper tools, or boatloads of therapy, it’s sort of too late.
The dude learns to sort of maybe claw feelings from the deep and kind of feel slivers of stuff, and he can sort of manufacture feelings or act like he’s got feelings, or set up limited contexts where he’s got feelings, and he can say the right words, but it’s sort of laborious, unnatural, etc. Maybe it’s enough, and maybe he’s gentle and safe and supportive but sad, or maybe he’s a “nice guy” and/or really angry underneath, because of what’s lost or what he can’t do.
The woman reads up on makeup and clothes, maybe takes a dance class, changes her hairstyle, goes to a spa, gets massages, explores herself in relationships or novels. But, there’s something awkward and clunky going on, she’s reaching for something that she wants to be and feel and naturally be seen as, but it doesn’t quite work or barely works.
You have a natural thing, that gets suppressed or controlled by a different thing that takes its place, and then a facsimile of the original natural thing goes on top. There can be more complicated structures and structures in parallel.
So the above is Deida shell or layer theory. Now to summarize/expand–
Sometimes the layer version is very, very, very smooth and functional, and it’s hard to tell that it’s a layer. Sometimes the person themself knows and other people don’t. And sometimes other people can tell, on some level, and the person themself doesn’t know. And maybe everybody knows or nobody knows.
If something takes a lot of energy to do, or feels unnatural, or laborious, or like one has to switch gears or gear up to do a thing, or that it’d be really easy to make a mistake, or that there’s barely room in one’s life for this and other things at the same time, or it’s taken over one’s life, or if it’s the most important thing one’s life, or if one has spent a lot of time on the theory of the thing, or read many books about the thing, or that it’s a lifestyle choice, or there’s a preoccupation with how other people aren’t doing the thing right, or they have other people who are or aren’t doing thing or who are the opposite of the thing, or they want to do the thing in highly ritualized way, or they fetishize something (in a sexual way or not), or the sacralize something (in a religious way or not) and so on, or they’re particularly rebellious about something or particularly conforming about something–all of that can be a sign that there’s shell/layer structure going on. In general the shell/layer will be patchily fabricated and take a lot of effort to maintain, even if that effort has become completely habitual.
I know that’s pretty intense. That’s almost everybody for something, in small and large ways. There are very common layer structures, including some shared by almost everyone in a particular culture.
Sometimes performers have exquisitely perfected shells, and that’s why we love them. Sometimes performers out of luckiness or unluckiness or extreme sacrifice or access to superlative training have either (early) prevented a shell from forming or (later) have made their way back to a real thing, and we love them for that expression of the real thing. (And there can be all sorts of complex interaction between layers and layers along different dimensions with the real thing peeking out in complex ways.)
Sometimes people can’t figure out how to create a functional shell and suffer terribly because they can’t be like the other people around them, for better or worse. And some people get a functional shell and of course suffer terribly throughout their lives because they can’t satisfactorily get access to what’s under the shell, and have to make do with ritualized structure to set up the right conditions if even that.
So, what to do?
Sometimes you maintain and take care of the layer, make it as healthy as it can be. And sometimes you take apart that fabricated version, as well as the shell underneath, get to the real version which will probably be frozen in time at a young age, and then help that young version grow up into the seamless, effortless adult version.
Both approaches have risks. There’s combinatorial complexity whatever one does. Sometimes there’s lots of low-hanging fruit, and/but sometimes undoing layers, the way things are all tangled up, can involve undoing a lot of functional structure, sometimes a LOT, stuff that was allowing a person to have friends and make money, and it can be a harrowing project of months or years or longer, depending on skill and intensity of investment, to untwist all the things that got twisted around and layered on top of each other.